Research On Spatial Modulation Techniques In Generalized Multiple-antenna Systems

In recent years, the research on multiple-antenna and cooperative communicationtechniques has drawn overwhelming attention, both in academia and industry.Multiple-antenna techniques, also called multiple-input multiple-output (MIMO)transmission techniques, can offer spatial multiplexing and/or diversity gains to thesystems in which multiple antennas are equipped at the transmitter and/or the receiver.In some scenarios, it is very difficult to equip multiple antennas due to the size,implementation complexity and power constraint of the mobile devices. In that case,the diversity gain can be provided by cooperative transmission schemes in which acollection of single-antenna terminals share antennas and other resources with eachother. Consequently, cooperative communication systems can be regarded asgeneralized MIMO systems.Spatial modulation (SM) and space shift keying (SSK) are low-complexityspatial multiplexing techniques for MIMO wireless system. The distinguishablefeature of SM/SSK is exploiting the spatial domain, which is constructed by multipleantennas, as an added source to convey information. In contrast to single-antennasystems, SM/SSK can offer improved spectral efficiency and enhanced robustness.Since inter-channel interference (ICI) is avoided and no inter-antenna synchronization(IAS) is required, the complexity of SM/SSK system is much lower than that ofconventional MIMO systems.In this thesis, the applications of SM/SSK concept in MIMO and cooperativecommunication systems are studied. Specifically, the adaptive spatial-constellationmapping mechanisms for MIMO systems are designed and the SSK transmissionschemes for multiple-relay networks are proposed. The main contributions of thethesis are summarized as follows.An adaptive spatial domain optimization technique for generalized space shiftkeying (GSSK) system is proposed. The concept of spatial domain defined by SSK isextended by GSSK scheme, in which the spatial constellation is constructed bycombinations of activated transmit antennas, rather than individual antennas. Thespectral efficiency of GSSK is much higher than that of SSK. Unfortunately, neitherSSK nor GSSK can achieve transmit diversity. Additionally, the spatial constellation of GSSK always contains redundant elements which are not used to conveyinformation. Based on these observations, in this dissertation, a novel adaptivemapping GSSK (AM-GSSK) technique is presented. In AM-GSSK system, the spatialconstellation is optimized according to the channel state information (CSI), and thesymbol error rate (SER) performance of the system is improved. To select the optimalspatial constellation, global optimization and local optimization algorithms areseparately presented. The analytical results indicate that AM-GSSK system canachieve transmit diversity.An adaptive signal-spatial domain joint optimization technique for generalizedspatial modulation (GSM) system is proposed. In GSM system, information bits areseparately mapped into the signal constellation and the spatial constellationconstructed by antenna combinations. Because of that, a novel adaptive joint mappingGSM (AJM-GSM) scheme is proposed, in which the signal constellation and thespatial constellation are jointly optimized. The global optimization and localoptimization algorithms are presented, respectively. The simulation results indicatethat the SER of the system can be reduced by AJM-GSM technique.In this thesis, the concept of SM/SSK is extended to the cooperativecommunication systems, and a cooperative space shift keying (CSSK) scheme formultiple-relay cooperative network is proposed. In CSSK system, the information ofthe source node is mapped into a distributed spatial domain constructed by multiplerelay nodes, and retransmitted to the destination node during the cooperative phase.Based on different working modes of the relay nodes, two CSSK protocols areseparately introduced: the demodulate-and-forward CSSK (DmF-CSSK) and thedecode-and-forward CSSK (DF-CSSK). The optimal detectors of the two protocolsare proposed, respectively. Moreover, a simplified piecewise-linear detector forDF-CSSK is presented. The achievable diversity of DF-CSSK system is analyzed.The performance of CSSK is validated by simulation results. Both the analytical andthe simulation results indicate that, as a low complexity cooperative transmissiontechnique for multiple-relay networks, CSSK exhibits unique advantages.