Design of a High-Performance CDMA-Based Broadcast-Free Photonic Multi-Core Network on Chip

Present-day focus on multicore research has not only increased computing power but also power- and bandwidth-efficient communication among cores. On-chip communication networks have become popular today because of their low energy use and modular structure compared to bus-based interconnects. Silicon photonics has further boosted the performance of on-chip interconnection networks with its low energy-delay product and high reliability. In current multicore Network-on-Chip (NoC) architectures, photonics is playing an important role in transferring large volumes of data both on- and off-chip. The problem addressed in this work is the issue of broadcast traffic arising due to invalidation requests from on-chip cache memories. Although such traffic is typically less than 1% of total traffic, it can easily present a high load on network resources, creating congestion and degrading performance. In this article, we propose a CDMA-based, secure, scalable, and energy-efficient technique to eliminate broadcast invalidations and increase overall performance. Experimental results indicate a performance boost up to 22.2% over a competing Photonic NoC and up to 57.4% over Electrical Mesh-based NoC when the proposed technique is used. Additional hardware deployed has an area overhead of less than 1%, whereas total energy consumed is at par with other state-of-the-art techniques.