Design and performance analysis of diversity schemes for spatial modulation and space shift keying systems

Novel single radio-frequency (RF) chain spatial modulation (SM) and space shift keying (SSK) systems are proposed as an alternative to conventional multiple-input multiple-output (MIMO) systems. In this thesis work, advanced SM/SSK systems are proposed and the performance of these systems is investigated and the advantages against the conventional MIMO systems are demonstrated. In this study, at first, the outage performance of point-to-point MIMO scheme combining SM with transmit antenna selection (TAS) is investigated in Nakagami-m channels for arbitrary m values. In this scheme, transmit antennas which maximize capacity of the system are selected for transmission and then SM is applied by using the selected transmit antennas. For this system, probability density function (PDF) of the received signal-to-noise ratio is derived and then, a closed-form expression for the outage probability of the system is derived by using this PDF. The asymptotic diversity analysis is also performed to demonstrate the achieved diversity order of the system. It is shown that outage performance of the system is improved when fading parameter m and/or number of transmit antennas increase. The derived analytical results are validated by Monte Carlo simulations. Besides the investigation of SM with TAS in Nakagami-m fading channels, due to its simplicity, good performance and low complexity, SSK is considered in the proposed schemes at the rest of the thesis. In this context, cooperative MIMO schemes combining SSK with TAS and relay selection, respectively, are proposed. In the cooperative MIMO scheme combining SSK with TAS, source transmit antennas are selected based on the Euclidean distances between source and destination channel fading coefficients. SSK is applied by using the selected transmit antennas. Besides the direct link transmission between source and destination, the relays which decode the signal transmitted from the source correctly, take part in the transmission. Exact expression and tight lower bound for symbol error rate (SER) of the proposed SSK system with TAS and cooperative relays are derived when the number of selected antennas is two and an arbitrary integer power of two, respectively. Moreover, an asymptotic diversity analysis for SER of the system is also performed to demonstrate the achievable diversity order of the system. It is shown that the proposed SSK system with TAS outperforms SSK system without TAS. It is also indicated that the proposed SSK system with TAS outperforms the conventional MIMO system, which employs antenna selection at source, for high data rates and sufficient number of receive antennas. On the other hand, in the cooperative MIMO scheme combining SSK with relay selection, SSK transmission is considered by using the source transmit antennas. In addition to the direct link transmission, a relay, which is selected according to partial relay selection technique, amplifies the data received from the source and forwards it to the destination. An exact and considerably accurate upper-bound expression for the average error probability of the proposed cooperative SSK system with relay selection are derived when the number of source transmit antennas is equal to two and an arbitrary integer power of two, respectively. An asymptotic diversity analysis is also performed to demonstrate the achievable diversity orders of the systems. It is shown that the proposed SSK system with partial relay selection outperforms the conventional cooperative single-input multiple-output (SIMO) system with partial relay selection. At the last chapter of the thesis, the performance of SSK modulation in multi-hop relay networks is investigated. In this context, the SSK is studied in three different multi-hop relay schemes. In the first scheme, a multi-hop multi-branch SSK system with amplify-and-forward (AF) cooperative relays is proposed. A MIMO scheme, in which source and destination are equip with multiple transmit and receive antennas, respectively, is considered. In this scheme, SSK is applied using the source transmit antennas and the single-antenna AF relays are used to amplify and forward the transmitted signals from the source to the destination in each hop of each branch. A considerably accurate lower-bound expression on the pairwise error probability of multi-hop single-branch SSK system and approximate expression on the bit error probability of multi-hop multi-branch SSK system are derived for the cases that numbers of transmit antennas are two and an arbitrary positive integer power of two at the source, respectively. It is shown that the proposed SSK system outperforms the classical single-input multiple-output systems for especially high data rates. The derived analytical results are validated by computer simulations. In the second scheme, SER analysis is performed for multi-hop SSK system with TAS. In this scheme, SSK is applied on the selected antennas at each hop. It is assumed that there is no line of sight transmission between source and destination and each receiving terminal decodes and forwards its received signal and maps the decided information bits to the selected antennas according to SSK modulation. For the proposed system, approximate and asymptotic SER expressions are derived and the theoretical results are verified by computer simulations. It is shown that the proposed system provides better error performance than the multi-hop SSK system without TAS, and it is also indicated that the proposed system outperforms conventional M-QAM system for especially high data rates and sufficient number of receive antennas at the destination. Finally, in the third scheme, a multi-hop decode-and-forward SSK system with path selection is proposed. In this scheme, the best path is selected among available multiple branches and source communicates with destination hop by hop through the relays of the selected path. SSK is applied by using source's and the relays' transmit antennas. Closed-form approximate and asymptotic SER expressions are derived for the proposed SSK system with path selection. Consequently, performance of the new proposed SM/SSK systems with diversity schemes is studied in this thesis. The advantages of SM/SSK systems with diversity schemes against the conventional MIMO systems are demonstrated. Moreover, analytical expressions corresponding to error probability of the proposed systems are derived. The derived analytical results are validated via comprehensive computer simulations.