Spatial Modulation With Multiple Active Transmit Antennas

This paper introduces Generalized spatial modulation with multiple active transmit antennas. This is a novel high rate low complexity MIMO transmission scheme. This will use multiple antennas to convey information, the extra information will encode in the physical location of transmitting antenna. So it can increase the transmission rate without using additional bandwidth. This system can achieve high diversity, high transmission rate and multiplexing gain. This system activates only a minimum number of antennas for transmission compared to MIMO, which helps to decrease the power consumption. Hence MA-SM make the communication system both energy efficient and spectral efficient. The minimum number of active antennas also reduces inter channel interference and inter antenna interference. The new system multiple active antenna spatial modulation (MA-SM) is a modification of MIMO technique. It is a novel high-rate, low complexity MIMO transmission scheme. The four communication models includes Single input single output (SISO), Multiple input single output (MISO), Single input multiple output (SIMO) and Multiple input multiple output (MIMO). MIMO system was introduced to overcome the drawbacks of three other previous techniques like SISO, MISO, and SIMO. MIMO has many advantages including spatial diversity; multiplexing and can improve reliability of communication by using multiple numbers of antennas. Data rate will linearly increase with the number of available transmitting antennas. But the increase of number of transmitting antennas beyond limit is not favorable. MIMO has got some limitation in terms of increasing the number of transmitting antennas. As the data transmits by multiple numbers of antennas it will create interference. So some powerful receivers are required to decode the streams of transmitted data, and also there should be a powerful synchronization between the antennas. The complexity of receiver should increase to get better performance. One of the main another issue in MIMO is increased power consumption. To get increased rate multiple antennas are required. Each antenna has RF chain. In a communication system power dissipation is mainly of two types, static power dissipation and dynamic power dissipation. Dynamic power dissipation is the power dissipation occurs during data transmission while static power is the power required to feed into RF chain to maintain the system in operating region. Static power loss occurs mostly in power amplifiers. In a communication system there will be RF chain associated with every antenna. Each RF chain has power amplifier. So as the number of antennas increases number of RF chain will increase, the number of power amplifier increase, hence the power dissipation. So in a MIMO system if the number of transmitting antenna increased for increasing data rate, the power required will be more. There should be a tradeoff between energy efficiency and spectral efficiency. So a new system is required which is efficient in terms of both energy and data rate. This requirement resulted in a new scheme of MIMO which is called spatial modulation. Then more efficient spatial modulation techniques like generalized spatial modulation and multiple active antenna spatial modulation introduced, which are modifications of spatial modulation.