Performance analysis of Link Adaptation with MIMO and varying modulation and coderates for 5G systems

5G is the fifth generation technology for mobile communication systems and it is the successor to 4G technology. 5G has been developed in order to cater for a mobile and connected environment. Link adaptation can be used to improve the performance of 5G systems. It deals with adapting the modulation scheme and coding rate of the error correcting code based on the radio link quality. This paper performs a comparative analysis of several link adaptation schemes. The performance of the 5G system was compared using 2-layer transmission with varying modulation and code-rates. Link adaptation is done at the modulation and coding process whereby a specific modulation index and/or code rate is chosen according to the Signal-to-Interference Noise Ratio (SINR) value in order to attain the maximum possible data rate corresponding to a target Bit Error Rate (BER). Results show that increasing code rates yields a higher BER for lower Signal-to-Noise Ratio (SNR) while increasing the data rate at higher SNR. A 5G with code-rate 340/1024 reached the target BER at SNR ldB with maximum data rate of 450.96 Mbps while a 5G system with code-rate 772/1024 reached the target BER at SNR 10 dB with maximum data rate of 1032.624 Mbps. Furthermore, link adaptation performed at modulation and code-rate level greatly improved the system performance as compared to a 5G system using static modulation and code-rate. The 5G system with code-rate 340/1024 reached a BER of 0.22 at SNR 3dB for 64 QAM, with data rate of 178 Mbps while the link adaptation scheme achieved the target BER of 1x10-8 with data rate of 225Mbps at the same SNR.