A game theoretical model for signature selection in non-cooperative IrLDS-OFDMA system

In irregular low density signature-orthogonal frequency division multiplexing (IrLDS-OFDM) random access system, since no uplink scheduling is performed, each user randomly picks one low density signature (LDS) with different density factor, and spreads the symbols with LDS in the time-frequency domain. In this paper, we propose a game theoretical model to describe this non-cooperative uplink multiple access. Specifically, the original multi-action game is decomposed into several degraded games for simplification. The strategies which achieve Nash equilibrium in the degraded games are then combined with certain rules, and as a result, a SNR threshold based density factor selection method is derived to achieve the Nash equilibrium. Simulations show that the proposed method can achieve better throughput than random signature selection.