## 5 Proposed WNoC Design  
### Design Concept  
The basic idea of WNoC is to incorporate an on-chip antenna into the core. This antenna modulates a signal, which is subsequently transferred at the speed of light, avoiding the need for several chip hops. Another on-chip antenna demodulates the signal at the receiving end. Various proposed WNoC systems operate in the 30-300 GHz frequency band, with data rates of several Gbps. To achieve greater bandwidth utilization, this system frequently incorporates modulation algorithms such as higher-order modulation, Quadratic Phase Shift Keying (QPSK), and Quadratic Amplitude Modulation (QAM). However, these schemes consume more power and require intricate transceiver circuits. On the contrary, in lower or non-coherent modulation techniques, such as on-off keying (OOK), the requirement for signal phase knowledge is not required and the receiver determines whether the transmitted symbol is a 0 or a 1 by comparing the power of the received signal strength against a threshold. Additionally, it can function with simpler transceiver circuits as depicted in Figure 2. It features a power amplifier (PA) and upconversion mixer on the transmitter side. On the receiver side, there is a low-noise amplifier (LNA), downconversion mixer, and injection-lock voltage-controlled oscillator (VCO) shared with the transmitter. This design eliminates the need for a power-hungry phase lock loop (PLL) by employing direct conversion and injection lock technology [38]. However, they come with limited bandwidth. To address these challenges, communication in the THz band, with its higher frequency bandwidth, becomes feasible [39]. The micrometer-sized THz on-chip antenna offers the advantage of high bandwidth and data rates in the terabit per second (Tbps) range. Several existing designs relying on Radio Frequency Complementary Metal-Oxide-Semiconductor (RF-CMOS) technology are currently accessible. In contrast with wired transmission lines, wireless communication is achievable in an omnidirectional fashion, enabling single-hop communication through broadcasting. This not only significantly diminishes power consumption but also facilitates faster communications. WNoC employs various multiplexing methods such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), and Spatial Multiplexing (SDM) to enhance the data rate of communications. These techniques contribute to the efficiency and speed of wireless communication within the network-on-chip architecture. To meet the low-latency requirements  
Figure 2: A simple block diagram of OOK transceiver. of a WNoC, additional logic functionalities should be implemented to determine whether signals should propagate through wired connections or wireless ones. In order to share the antenna among many cores, a routing algorithm proposed by [40], called the radio access control mechanism (RACM), reduces communication delay by 30% and saves energy by 25% under real and synthetic traffic scenarios. Another algorithm proposed by [41] utilizes a hybrid form of communication, i.e., wired and wireless interconnection, depending on the distances between the cores, thereby improving communication efficiency. A routing technique called adaptive WNoC, developed by [42], aims to reduce traffic at wireless routers by monitoring buffer occupancy. The results show significant improvement in packet latency as the network size increases. In the event of wireless interconnect failure, which poses significant risk and increases delay, a novel adaptive fault-tolerant wireless routing algorithm proposed by [43] routes packets through alternative hubs with high average hop counts, demonstrating improvements in congestion and resilience. A new routing algorithm called HoenyWiN, proposed in [44], outperforms traditional mesh-type networks in terms of delay, throughput, and energy consumption. This routing algorithm avoids long multi-hop wired paths by utilizing the nearest wireless interconnect.