A Bandwidth Control Arbitration for SoC Interconnections Performing Applications with Task Dependencies

Current System-on-Chips (SoCs) execute applications with task dependency that compete for shared resources such as buses, memories, and accelerators. In such a structure, the arbitration policy becomes a critical part of the system to guarantee access and bandwidth suitable for the competing applications. Some strategies proposed in the literature to cope with these issues are Round-Robin, Weighted Round-Robin, Lottery, Time Division Access Multiplexing (TDMA), and combinations. However, a fine-grained bandwidth control arbitration policy is missing from the literature. We propose an innovative arbitration policy based on opportunistic access and a supervised utilization of the bus in terms of transmitted flits (transmission units) that settle the access and fine-grained control. In our proposal, every competing element has a budget. Opportunistic access grants the bus to request even if the component has spent all its flits. Supervised debt accounts a record for every transmitted flit when it has no flits to spend. Our proposal applies to interconnection systems such as buses, switches, and routers. The presented approach achieves deadlock-free behavior even with task dependency applications in the scenarios analyzed through cycle-accurate simulation models. The synergy between opportunistic and supervised debt techniques outperforms Lottery, TDMA, and Weighted Round-Robin in terms of bandwidth control in the experimental studies performed.

Spectrum Handoff Mechanism in the Framework of Mobility Management in Cognitive Radio Networks

Cognitive radio appears as an innovative technology in the field of access to wireless systems, aimed at significantly improving the use of the radio spectrum by allowing an opportunistic access manner. This article deals with some of the important characteristics of the spectrum mobility in cognitive radio networks (CRNs).The new management approach to the mobility and the connection are designed to reduce the latency and loss of information during spectrum handoff. A list of channel safeguards are maintained in this effect, but the maintenance and updates are a challenge. In this article, the authors describe the reasons and mechanisms for spectrum handoff. Algorithms have been developed to illustrate this handoff mechanism and make the comparison between the different methods of spectrum handoff. The simulation results obtained confirm that the proposed method and the algorithms developed presents a better performance.

Uma proposta para a melhoria da descoberta de vizinhos em Redes Cognitivas

Several wireless services make use of the spectrum for communication, from space radio communication to a simple wireless computer network. However, the considerable amount of services that make use of spectrum in the last years, has been responsible for its limited availability and inefficiency.. Cognitive networks or cognitive radio networks, are a technology that offer the efficient use of spectrum through opportunistic access to frequency bands. Throughout the cognitive radios scenario, this work will present a variation of the JENNA neighbors discovery algorithm. In addition to that, this research will propose a sensing model for a more efficient approach.