This paper proposes an algorithm to design rate-adaptive irregular LDPC codes with improved Bit error rate (BER) performance. It focuses on achieving better BER results for higher order coding rates which are in high demand for 5G mobile communications. The algorithm generates a parity check matrix based on the message block size. The encoding complexity of the irregular LDPC code is comparatively reduced due to the proposed parity check matrix. Simulation results compare the BER performances of irregular LDPC codes for various code rates and modulation schemes with the Parity check matrix (PCM) generated by the proposed algorithm. The BER performance of improved irregular LDPC code is analyzed in a real-time scenario using Software Defined Radio platform as well.