It is required that on the previous cooperative MIMO system, the cooperation protocol of the relay is changed to the decoding and forwarding strategy and the coding cooperation strategy respectively, and the previous irregular LDPC coding is used to compare with the amplified forwarding protocol to make a bit error rate graph (source node 1 a, a relay, a destination node, the antenna is a case, the comparison of three different bit error rate is relatively FIG relay protocol) and the outage probability FIG.
I.e. irregular LDPC , the source node and the 1 th, a relay, a destination node, the antenna is a comparison of three kinds of relay cooperation protocol error rate situation.
As a relay protocol in the form of coding cooperation for irregular LDPC codes, compare the bit error rate graph and the outage probability graph in the following three cases:
One source node (one antenna is configured), four relay nodes (one antenna is configured for each node), and one destination node (one antenna is configured for the node) (1:4:1)
2 source nodes, 4 relay nodes, and 1 destination node (2:4:1)
1 source node, 4 relay nodes, 2 destination nodes (1:4:2)
·141·241·142
The final BER simulation result is shown in the figure below:
It can be seen from the above simulation results:
·The number of transmitting antennas is fixed, and when the signal-to-noise ratio is unchanged, the performance will increase with the increase of the number of receiving antennas, but the improved capability
It can be seen from the above simulation results:
·When the number of transmitting antennas is constant, the performance will increase with the increase of the number of receiving antennas when the signal-to-noise ratio is unchanged, but the improvement will be slower and slower.
·When the number of receiving antennas is constant and the noise ratio is unchanged, the performance will increase with the increase of the number of transmitting antennas, but the improvement will be slower and slower.
With irregular LDPC encoding, in the cooperative MIMO system, the relay node processes the signal with the amplifying and forwarding protocol . When the relay receives the source end signal and forwards it to the destination node, beamforming technology is added in the two processes , and there is no addition. System comparison of beamforming technology, make a graph of bit error rate ( 2 source nodes, 4 relay nodes , 2 destination nodes ) (beamforming algorithm uses SVD method, that is, the singular value decomposition of the channel matrix)
System structure without beamforming:
System structure for beamforming:
That is, the beamforming technology is added to the two positions of the transmission source of 2 antennas and 4 relay nodes, and 4 relay nodes and 2 receiving antennas. Here, the original relay without beamforming has been improved, and the simulation results are as follows:
On the basis of the third figure, under the same conditions, the beamforming algorithms of the relay node use SVD, MMSE and SVD-MMSE hybrid algorithms respectively. These three algorithms are applied to the system and their bit error rates are compared. . (For the details of the three algorithms, see References)
