Beyond 5G communication systems are expected to satisfy substantially improved performance. Especially 6G is expected to deal with more stringent energy efficiency, latency and rate targets. Index modulation assisted schemes are one of the popular choices for next generation wireless communication systems and efforts are being made in all dimensions to improve its performance. Both the spatial modulation schemes and OFDM with index modulation belong to this class, which offer better BER, energy efficiency etc. Towards this, we propose two techniques. The first one being a multilayer architecture for OFDM with index modulation (OFDM-IM). For coherent OFDM-IM, we propose three different schemes; 1) multilayer index modulation (MIM); 2) dual mode MIM; and 3) compressive sampling aided MIM. The scheme strikes a compelling tradeoff between the BER, energy efficiency and throughput. Subsequently, we extend this multilayer framework to non-coherent OFDM-IM. We also propose a precoding scheme for peak-to-average power ratio (PAPR) reduction in non-coherent OFDM-IM. Secondly, we combine the intelligent reflecting surface (IRS) and millimeter wave solutions to propose a spatial modulation scheme, namely beam index modulation for use in 6G systems. IRS is a popular choice for reducing power consumption and hardware cost, whereas millimeter frequency can be used for improving spectral efficiency. Three different architectures exploiting a pair of IRS have been investigated. We derive theoretical bounds for the various proposed schemes and compare them with extensive simulation studies.