ABSTRACT
Collaborative beamforming (CBF) enables distributed nodes to act as a large antenna array to collaboratively transmit a common signal to a common target. The promise of low-power consumption and high transmit range makes CBF a suitable candidate for future network communications such as the Internet of Things (IoT) and machine-to-machine (M2M) communications. Due to the distributed nature of the nodes in CBF, synchronization in CBF remains a challenging topic in the research community. In this chapter, a new algorithm called Combined Hybrid Distributed Joint Activation (CDJA-HYB) based on population-based metaheuristic algorithms is introduced to enable phase synchronization in closed-loop CBF with limited feedback. The algorithm adopts the synchronization process of two existing synchronization algorithms called the random one-bit feedback (R1BF) and the advanced deterministic joint activation (ADJA) method. However, the controlled randomization inspired by population-based meta-heuristics in the proposed CDJA-HYB allows faster and better synchronization of nodes for CBF. The algorithm is tested under noisy, time-varying, and shadowing effects and the results show that the proposed algorithm achieves better convergence rate and maximum achievable signal strength when compared with the legacy distributed beamforming synchronization algorithms.
