In application-specific SoCs, the irregularity of the topology ends up in a complex and customized implementation of the routing algorithm, usually relying on routing tables implemented with memory structures at source end nodes. As system size increases, the routing tables also increase in size with nonnegligible impact on power, area, and latency overheads. In this paper, we present a routing implementation for application-specific SoCs able to implement in an efficient manner (with no routing tables and using a small logic block in every switch) a deadlock-free routing algorithm in these irregular networks. The mechanism relies on a tool that maps the initial irregular topology of the SoC system into a logical regular structure where the mechanism can be applied. We provide details for both the mapping tool and the proposed routing mechanism. Evaluation results show the effectiveness of the mapping tool as well as the low area and timing requirements of the mechanism. With the mapping tool and the routing mechanism, complex irregular SoC topologies can now be supported without the need for routing tables.

This paper presents the design and the characterization in nanoscale CMOS technology of a Network Interface (NI) for on-chip communication infrastructure with hardware support of advanced networking functionalities: store & forward (S&F) transmission, error management, power management, ordering handling, security, QoS management, programmability, end-to-end protocol interoperability, remapping. The design has been conceived as a scalable architecture: The advanced features can be added on top of a basic NI core implementing data packetization and conversion of protocols, frequency and data size between the connected Intellectual Property (IP) core and the on chip network. The NI can be configured to reach the desired tradeoff between supported services and circuit complexity.

In application-specific SoCs, the irregularity of the topology ends up in a complex implementation of the routing algorithm, usually relying on routing tables implemented with memory structures. As system size increases, the routing table increases in size with non-negligible impact on power, area and latency overheads. In this paper we present a routing implementation for application-specific SoCs able to implement in an efficient manner (without requiring routing tables and using a small logic block in every switch) a routing algorithm in these irregular networks. The mechanism relies on a tool that maps the initial irregular topology of the SoC system into a logical regular structure where the mechanism can be applied. We provide details on the mapping tool as well the proposed routing mechanism. Evaluation results show the effectiveness of the mapping tool as well as the low area and timing requirements of the mechanism. With the mapping tool and the routing mechanism complex irregular SoC topologies can now be supported without the use of routing tables.

Scaling down in very deep submicron (VDSM) technologies increases the delay, power consumption of on-chip interconnects, while the reliability and yield decrease. In high performance integrated circuits wires become the performance bottleneck and we are shifting towards communication centric design paradigms. Networks-on-chip and stacked 3D integration are two emerging technologies that alleviate the performance difficulties of on-chip interconnects in nano-scale designs. In this paper we present a design-time configurable error correction scheme integrated at link-level in the 3D Spidergon STNoC on-chip communication platform. The proposed scheme detects errors and selectively corrects them on the fly, depending on the critical nature of the transmitted information, making thus the correction software controllable. Moreover, the proposed scheme can correct multiple error patterns by using interleaved single error correction codes, providing an increased level of reliability. The performance of the link and its cost in silicon and vertical wires are evaluated for various configurations.

Connection-then-credits (CTC) is a novel end-to-end flow control protocol to handle message-dependent deadlocks in best-effort networks-on-chip (NoC) for embedded multicore systems-on-chip (SoCs). CTC is based on the classic end-to-end credit-based flow control protocol but differs from it because it uses a network interface microarchitecture where a single credit counter and a single input data queue are shared among all possible communications. This architectural simplification reduces the area occupation of the network interfaces and increases their design reuse; for instance, the same network interface can be used to connect a core independently of the number of incoming and outgoing communications. CTC, however, requires a handshake preamble to initialize the credit counter in the sender network interface based on the buffering capacity of the receiver network interface. While this necessarily introduces a latency overhead in the transfer of a message, simulation-based experimental results show that the penalty in performance is limited when large messages need to be transferred, thus, making CTC a valid solution for particular classes of applications such as video stream processing.

We propose Connection then Credits (CTC) as a new end-to-end flow control protocol to handle message-dependent deadlocks in networks-on-chip (NoC) for multicore systems-on-chip. CTC is based on the classic end-to-end credit-based flow control protocol but differs from it because it uses a network interface micro-architecture where a single credit counter and a single input data queue are shared among all possible communications. This architectural simplification reduces the area occupation of the network interfaces and increases their design reuse: for instance, the same network interface can be used to connect a core independently of the number of incoming and outgoing communications. CTC, however, requires a handshake preamble to initialize the credit counter in the sender network interface based on the buffering capacity of the receiver network interface. While this necessarily introduces a latency overhead in the transfer of a message, simulation-based experimental results show that the penalty in performance is limited when large messages need to be transferred, thus making CTC a valid solution for particular classes of applications such as video stream processing.

Reconfigurable architectures and NoC (Network-on-Chip) have introduced new research directions for technology and flexibility issues, which have been largely investigated in the last decades. Exploiting run-time adaptivity opens a new area of research by considering dynamic reconfiguration. In this paper, we present the architecture and associated development tools of an heterogeneous reconfigurable SoC focusing on the chosen communication infrastructure. The SOC integrates units of various sizes of reconfiguration granularity. The included NoC approach demonstrates the mentioned benefits and scalability for actual and future SoC design. On a reference CMOS090 implementation the described interconnect system works at the system reference frequency of 200 MHZ sustaining the required run-time bandwidth on a set of reference applications, at a price ≪ 10% in area in power consumption with respect to the overall system.

This work presents a low-complexity physical link micro architecture for a mesochronous on-chip communication insensitive to clock skew. This new link architecture, called LIME, integrates a low-latency flow control scheme; this feature may ease the set up of reliable Network-on-Chip infrastructures. The proposed architecture also supports virtual channels that are multiplexed on a single physical link. LIME can be integrated in a conventional digital design flow since it is implemented by means of standard cells only.

Clock distribution is an important issue when designing multi processor systems-on-chip on deep sub-micron technology nodes and non-synchronous approaches are becoming popular in this field. This work presents a low-complexity link microarchitecture for mesochronous on-chip communication that enables skew constraint looseness in the clock tree synthesis, frequency speed-up, power consumption reduction and faster back-end turnarounds. With respect to the state of the art, the proposed link architecture stands for its low power and low complexity overheads; moreover it can be easily integrated in a conventional digital design flow since it is implemented by means of standard cells only. Results are presented referring to the link integrated within a multi processor tiled architecture based on a network-on-chip communication backbone on a CMOS 65 nm technology.

Application-specific network-oriented communication architectures have recently become an effective solution to support high bandwidth Systems on-Chip. The Network on-Chip architectures considered so far range from regular to fully customized topologies for application-specific designs requiring high-level bandwidth. To this end, a network-centric design flow is necessary to support the design space exploration of complex SoCs with tight design constraints. This paper introduces four different approaches based on the orthogonalization of core mapping and topology customization applied to STNoC, the Network on-Chip developed by STMicroelecronics. The four methods are derived from the combination of the initial mappings to two standard topologies (ring and spidergon) with two types of topology customization based on the insertion of cross-links to reduce the network distance of standard topologies.

NoC architectures are considered the next generation of communication infrastructure for future systems-on- chip. Selection of the network architecture and mapping of IP nodes onto the NoC topology are two important research topics. In this paper we compare well known NoC interconnect systems, specifically, Ring, 2d-Mesh, Spidergon and unbuffered Crossbar using theoretical uniform traffic based on the request/reply paradigm as well as a realistic traffic based on a Mpeg4 application. The IP mapping is computed by the SCOTCH partitioning tool opportunely modified to maximize selected embedding quality criteria under multiple topological constraints.

Customized network-oriented communication architectures have recently become a must to support high bandwidth SoCs. To this end, a corresponding communication design flow is necessary to support the design space exploration of complex SoCs with tight design constraints. In order to exploit the benefits introduced by the NoC approach for the on-chip communication, the paper presents a Pareto Simulated Annealing (PSA) approach for the customization of the network topology. The proposed PSA approach has been applied to STNoC, the Network on-Chip developed by STMicroelectronics. Starting from the ring topology, the proposed application-specific design flow tries to find a set of customized topologies (optimized in terms of performance and area/energy overhead) by adding custom links up to the spidergon topology.

In this paper, a digital RFI (radio frequency interference) canceller for DMT (discrete multitone modulation)-based VDSL (very high-speed digital subscriber line) systems is presented. The adopted algorithm is optimized in terms of performance vs. complexity and size of the involved memories. High level, maximum precision system simulations showed the effectiveness of the cancellation scheme, considering VDSL performance parameters such as bit rate and efficiency in counteracting performance degradation due to RFI. The canceller has been implemented as a hardware macro-cell: the design space already explored at algorithm level to meet a good complexity/performance trade-off, has been deeply investigated during the bit true analysis to fix the finite numeric representation, the micro-architecture definition and the final technology mapping. Results of logic synthesis on a standard cells 0.18 /spl mu/m CMOS technology are reported, in terms of area and energy consumption.

The Permanent Scatterers (PS) technique is an advanced tool for processing series of interferometric SAR data aiming at millimetric precision ground deformation mapping. The approach is based on a joint time-space-acquisition geometry analysis that is carried out at individual point-wise radar targets. The aim of this paper is twofold: (1) describe the main issues related to the precision of PS products; (2) show preliminary PS results obtained using, instead of ESA-ERS scenes, data acquired by other spaceborne SAR platforms characterized different acquisition parameters (namely RADARSAT and JERS).

The detection of ground deformation phenomena exhibiting a time non-uniform behavior by means of the permanent scatterers technique is addressed. Simple but effective models are discussed showing significant results obtained.