Software-defined wireless sensor networks are emerging as a transformative technology for industrial, research, and IoT applications leveraging their control-data plane separation. This paper analyzes routing protocols, emphasizing their advantages, limitations, and QoS-impacting factors (e.g., latency, bandwidth, among others). Through a systematic review, we identify innovative solutions to enhance QoS in SDWSNs, addressing challenges like energy efficiency and dynamic adaptability. Previous results demonstrate that centralized routing and machine learning-based algorithms significantly improve reliability in critical applications.