<p>The evolving wireless communications landscape necessitates innovative schemes to enhance efficiency and reliability. Rate-splitting multiple access (RSMA) is a promising approach for future generations, enabling the division of user data into common and individual private components. These data streams are combined at the base station (BS) with appropriate power distribution for each message, and successive interference cancellation (SIC) at the receiver is typically required to separate the common message from the combined data. However, SIC introduces complexity and potential performance degradation. To address these challenges, we propose space-shift keying (SSK) modulation to transmit the common message while using M-ary modulation for private messages, eliminating the need for SIC and reducing power consumption. Meanwhile, intelligent reflecting surfaces (IRS) are emerging as a key technology for next-generation communication systems, and their integration into RSMA further enhances system performance. Here, we derive exact and upper bound expressions for the average bit error rate (ABER) for both near user (NU) and cell edge user (CEU) within a cell using SSK modulation in an IRS-assisted RSMA system. Our analytical results are validated through comparison with Monte Carlo simulation results, demonstrating the efficacy and reliability of the proposed system model. </p>