Cooperative reception diversity apparatus and method based on signal point rearrangement or superposition modulation in relay system

A computing device-implemented method for cooperative reception diversity based on superposition modulation in a reception unit of a relay system, comprising:

• calculating a Log-Likelihood Ratio (LLR) of the symbol when a certain superposition-modulated symbol is received from a transmitting unit, the symbol modulated with a first type of superposition modulation;
• calculating an LLR of a symbol modulated at the relay station using a different type of superposition modulation from the first type of superposition modulation used in the transmitting unit when the symbol modulated using the different superposition modulation is received from a relay station;
• and
• summing and combining an LLR of each symbol received through the transmitting unit and relay station.

A computing device-implemented method for cooperative reception diversity based on signal point rearrangement in a relay station of a relay system, comprising:

• receiving a symbol mapped with a certain signal point constellation from a transmitting unit;
• demodulating the received symbol and decoding the demodulated symbol to output a message bit;
• and
• rearranging the signal point of the message bit at the relay station to be different than the signal point constellation arranged in the transmitting unit and relaying to a reception unit.

A computing device-implemented method for cooperative reception diversity based on signal point rearrangement in a reception unit of a relay system, comprising:

• calculating a Log-Likelihood Ratio (LLR) of the symbol when a symbol mapped with a certain signal point constellation is received from a transmitting unit;
• calculating an LLR of a symbol with rearranged signal point when the symbol with the rearranged signal point is received from a relay station, the rearranged signal point rearranged at the relay station;
• and
• summing and combining an LLR of each symbol received through the transmitting unit and relay station.

A relay station in a relay system for providing cooperative reception diversity, comprising:

• a demodulator to demodulate a certain superposition-modulated symbol when the certain superposition-modulated symbol is received from a transmitting unit;
• a decoder to decode the symbol demodulated through the demodulator, to output a message bit;
• an encoder to perform channel-encoding of the message bit;
• and
• a modulator to modulate the encoded message bit using a type of superposition modulation different from a first type of superposition modulation used in the transmitting unit.