RCAS: Critical Load Based Ranking for Efficient Channel Allocation in Wireless NoC

Multiple wireless hubs on a wireless network-on-chip (WNoC) share a single channel for simple implementation and to keep the overhead low. The traditional timer-based token passing mechanism that is responsible for channel allocation to hubs, treats all the packets taking the wireless path equally. However, the critical packets can stall the execution of applications or increase memory access time if not served with priority. The timer based approach also assigns the channel to each of the wireless hubs for a fixed time slot. This results in degraded system performance and inefficient wireless resource utilization. In this work, we propose RCAS, a Ranking based Channel Allocation Scheme that assigns the channel to the wireless hubs according to their rank. The critical nature of load along with total load size at each wireless hub decides its position in the ranking table. This enables the system to best utilize the wireless medium by reducing the channel idle time while keeping the network quality-of-service (QoS) in priority. Evaluation of the proposed scheme shows an average improvement of 9.5% in wireless medium utilization and an average reduction of 33.2% in critical load delay in comparison to a traditional timer-based approach.