Spatial modulation (SM) is a multi-input-multi-output (MIMO) technique that ex- ploits the channel state information (CSI) to transmit information using only one antenna at a time. Space shift keying (SSK) is a special case of SM, in which only the space domain is used for transmission. The combination of SM/SSK with exist- ing performance enhancement techniques has been studied because of its potential to achieve additional performance gains. In this thesis, we investigate the use of the CSI in SM and SSK in two aspects, namely, the combination of SM/SSK with bit-mapping and with trellis coded modulation (TCM). In the first part of the thesis, we propose a novel low-complexity adaptive bit mapping scheme for SM called the nearest point method (NPM). In this scheme, the SM symbols are first sorted according to a certain sorting order; then, bit sequences that are different only in one bit are assigned to subsequent SM symbols according to that sorting order. To determine the sorting order, NPM starts with the pair of SM symbols that has the minimum distance. From one of the SM symbols in that pair, it identifies the nearest SM symbol and continues to do so until it visits all the SM symbols without visiting the same SM symbol twice. Simulation results show that NPM achieves performance close to the lower bound of the bit error rate (BER) for SM and space shift keying (SSK) using full CSI at the transmitter (CSIT). It also achieves BER improvement for SSK using partial CSIT. The complexity of the proposed NPM is on the order of O(K2), where K is the number of symbols, which is remarkably low. In the second part of the thesis, we investigate a trellis coded space shift keying modulation scheme, called trellis coded space-time shift keying (TC-STSK), which combines trellis coded modulation (TCM) with space shift keying (SSK). By analyzing the rank criteria of the TC-STSK scheme using a graph theoretic approach, we try to maximize the number of unique differences between pairwise codewords as the code design goal. We discuss the code design principles for achieving diversity, and propose a design algorithm that is mostly suitable for rate-1/n codes, where n is the number of the code output bits. We also propose a diversity adaptation mechanism by selecting only the codewords with desired diversity, and we use it to achieve full diversity. We then provide the encoder design and a modified soft Viterbi decoder for such schemes. Simulation results show that the proposed scheme can achieve diversity orders expected from theoretical analysis, and decreasing the bit rate and increasing the number of shift registers and transmit antennas improves the performance of the TC-STSK scheme. The results also show that TC-STSK outperforms the space-time trellis code (STTC) for the same bit rate and number of shift registers.