Optimal Power Allocation for Channel Estimation in Spatial Modulation
Résumé
This work investigates the impact of power allocation for channel estimation (CE) in spatial modulation (SM). SM is a unique single-stream multiple-input multiple-output (MIMO) transmission technique that achieves spatial multiplexing gains. While SM completely avoids inter-channel interference, a single active antenna leads to a challenge for CE, i.e., all transmit antennas have to be activated sequentially to send the pilot signal. More time as well as energy is therefore consumed for CE. Driven by this motivation, we propose a closed-form optimal power allocation (OPA) for SM in this paper. Regardless of the SM transceiver structure, the optimal solution only depends on the pilot sequence length and the ratio between the number of pilots and the number of total symbols. Simulations results show that the bit error ratio performance of OPA-based SM tightly approaches the case of perfect channel state information with a gap of less than 0.8 dB.