A bandwidth efficient coding technique for spatial modulation and its error performance

The need for high data rate and high spectral efficiency are the key elements that drive research in future wireless communication systems. Power and bandwidth are limited resources in wireless communication systems. There has been a great improvement in system spectral efficiency with the advent of MIMO (multiple-input-multiple-output) techniques. The use of multiple antennas at the transmitter and receiver sides can cause an increase in the capacity and reliability of wireless links. But multi-antenna operation faces some challenges due to complexity and cost of the hardware owing to the requirement of inter-antenna synchronization and maintenance of multiple radio-frequency (RF) chain. Spatial modulation (SM) is a relatively new modulation technique for multiple antenna systems which deal with these issues. Spatial modulation (SM), utilizes the multiple transmit antennas in a different way. Multiple antennas are considered as additional constellation points that are used to carry information bits. In this only one antenna will be active at a time and the active antenna index will be transmitted along with the information bits. The novel idea in this paper is to encode the antenna index by trellis coded modulation (TCM). TCM is a method of reducing power requirements without increasing bandwidth. This method is known as trellis coded spatial modulation (TCSM). The performance of TCSM is compared to the performance of SM, V-BLAST (vertical Bell Labs layered space-time) and Alamouti scheme in AWGN and Spatial correlation channel. The programming and simulation is done using MATLAB.