System-on-chip Computing and Interconnection Architectures for Telecommunications and Signal Processing

This dissertation proposes novel architectures and design techniques targeting SoC building blocks for telecommunications and signal processing applications. Hardware implementation of Low-Density Parity-Check decoders is approached at both the algorithmic and the architecture level. Low-Density Parity-Check codes are a promising coding scheme for future communication standards due to their outstanding error correction performance. This work proposes a methodology for analyzing effects of finite precision arithmetic on error correction performance and hardware complexity. The methodology is throughout employed for co-designing the decoder. First, a low-complexity check node based on the P-output decoding principle is designed and characterized on a CMOS standard-cells library. Results demonstrate implementation loss below 0.2 dB down to BER of 10^{-8} and a saving in complexity up to 59% with respect to other works in recent literature. High-throughput and low-latency issues are addressed with modified single-phase decoding schedules. A new "memory-aware" schedule is proposed requiring down to 20% of memory with respect to the traditional two-phase flooding decoding. Additionally, throughput is doubled and logic complexity reduced of 12%. These advantages are traded-off with error correction performance, thus making the solution attractive only for long codes, as those adopted in the DVB-S2 standard. The "layered decoding" principle is extended to those codes not specifically conceived for this technique. Proposed architectures exhibit complexity savings in the order of 40% for both area and power consumption figures, while implementation loss is smaller than 0.05 dB. Most modern communication standards employ Orthogonal Frequency Division Multiplexing as part of their physical layer. The core of OFDM is the Fast Fourier Transform and its inverse in charge of symbols (de)modulation. Requirements on throughput and energy efficiency call for FFT hardware implementation, while ubiquity of FFT suggests the design of parametric, re-configurable and re-usable IP hardware macrocells. In this context, this thesis describes an FFT/IFFT core compiler particularly suited for implementation of OFDM communication systems. The tool employs an accuracy-driven configuration engine which automatically profiles the internal arithmetic and generates a core with minimum operands bit-width and thus minimum circuit complexity. The engine performs a closed-loop optimization over three different internal arithmetic models (fixed-point, block floating-point and convergent block floating-point) using the numerical accuracy budget given by the user as a reference point. The flexibility and re-usability of the proposed macrocell are illustrated through several case studies which encompass all current state-of-the-art OFDM communications standards (WLAN, WMAN, xDSL, DVB-T/H, DAB and UWB). Implementations results are presented for two deep sub-micron standard-cells libraries (65 and 90 nm) and commercially available FPGA devices. Compared with other FFT core compilers, the proposed environment produces macrocells with lower circuit complexity and same system level performance (throughput, transform size and numerical accuracy). The final part of this dissertation focuses on the Network-on-Chip design paradigm whose goal is building scalable communication infrastructures connecting hundreds of core. A low-complexity link architecture for mesochronous on-chip communication is discussed. The link enables skew constraint looseness in the clock tree synthesis, frequency speed-up, power consumption reduction and faster back-end turnarounds. The proposed architecture reaches a maximum clock frequency of 1 GHz on 65 nm low-leakage CMOS standard-cells library. In a complex test case with a full-blown NoC infrastructure, the link overhead is only 3% of chip area and 0.5% of leakage power consumption. Finally, a new methodology, named metacoding, is proposed. Metacoding generates correct-by-construction technology independent RTL codebases for NoC building blocks. The RTL coding phase is abstracted and modeled with an Object Oriented framework, integrated within a commercial tool for IP packaging (Synopsys CoreTools suite). Compared with traditional coding styles based on pre-processor directives, metacoding produces 65% smaller codebases and reduces the configurations to verify up to three orders of magnitude

Pre-validation of SoC via hardware and software co-simulation

Abstract. System-on-chips (SoCs) are complex entities consisting of multiple hardware and software components. This complexity presents challenges in their design, verification, and validation. Traditional verification processes often test hardware models in isolation until late in the development cycle. As a result, cooperation between hardware and software development is also limited, slowing down bug detection and fixing. This thesis aims to develop, implement, and evaluate a co-simulation-based pre-validation methodology to address these challenges. The approach allows for the early integration of hardware and software, serving as a natural intermediate step between traditional hardware model verification and full system validation. The co-simulation employs a QEMU CPU emulator linked to a register-transfer level (RTL) hardware model. This setup enables the execution of software components, such as device drivers, on the target instruction set architecture (ISA) alongside cycle-accurate RTL hardware models. The thesis focuses on two primary applications of co-simulation. Firstly, it allows software unit tests to be run in conjunction with hardware models, facilitating early communication between device drivers, low-level software, and hardware components. Secondly, it offers an environment for using software in functional hardware verification. A significant advantage of this approach is the early detection of integration errors. Software unit tests can be executed at the IP block level with actual hardware models, a task previously only possible with costly system-level prototypes. This enables earlier collaboration between software and hardware development teams and smoothens the transition to traditional system-level validation techniques.Järjestelmäpiirin esivalidointi laitteiston ja ohjelmiston yhteissimulaatiolla. Tiivistelmä. Järjestelmäpiirit (SoC) ovat monimutkaisia kokonaisuuksia, jotka koostuvat useista laitteisto- ja ohjelmistokomponenteista. Tämä monimutkaisuus asettaa haasteita niiden suunnittelulle, varmennukselle ja validoinnille. Perinteiset varmennusprosessit testaavat usein laitteistomalleja eristyksissä kehityssyklin loppuvaiheeseen saakka. Tämän myötä myös yhteistyö laitteisto- ja ohjelmistokehityksen välillä on vähäistä, mikä hidastaa virheiden tunnistamista ja korjausta. Tämän diplomityön tavoitteena on kehittää, toteuttaa ja arvioida laitteisto-ohjelmisto-yhteissimulointiin perustuva esivalidointimenetelmä näiden haasteiden ratkaisemiseksi. Menetelmä mahdollistaa laitteiston ja ohjelmiston varhaisen integroinnin, toimien luonnollisena välietappina perinteisen laitteistomallin varmennuksen ja koko järjestelmän validoinnin välillä. Yhteissimulointi käyttää QEMU suoritinemulaattoria, joka on yhdistetty rekisterinsiirtotason (RTL) laitteistomalliin. Tämä mahdollistaa ohjelmistokomponenttien, kuten laiteajureiden, suorittamisen kohdejärjestelmän käskysarja-arkkitehtuurilla (ISA) yhdessä kellosyklitarkkojen RTL laitteistomallien kanssa. Työ keskittyy kahteen yhteissimulaation pääsovellukseen. Ensinnäkin se mahdollistaa ohjelmiston yksikkötestien suorittamisen laitteistomallien kanssa, varmistaen kommunikaation laiteajurien, matalan tason ohjelmiston ja laitteistokomponenttien välillä. Toiseksi se tarjoaa ympäristön ohjelmiston käyttämiseen toiminnallisessa laitteiston varmennuksessa. Merkittävä etu tästä lähestymistavasta on integraatiovirheiden varhainen havaitseminen. Ohjelmiston yksikkötestejä voidaan suorittaa jo IP-lohkon tasolla oikeilla laitteistomalleilla, mikä on aiemmin ollut mahdollista vain kalliilla järjestelmätason prototyypeillä. Tämä mahdollistaa aikaisemman ohjelmisto- ja laitteistokehitystiimien välisen yhteistyön ja helpottaa siirtymistä perinteisiin järjestelmätason validointimenetelmiin

The COMPLEX reference framework for HW/SW co-design and power management supporting platform-based design-space exploration

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Comparative performance evaluation of latency and link dynamic power consumption modelling algorithms in wormhole switching networks on chip

The simulation of interconnect architectures can be a time-consuming part of the design flow of on-chip multiprocessors. Accurate simulation of state-of-the art network-on-chip interconnects can take several hours for realistic application examples, and this process must be repeated for each design iteration because the interactions between design choices can greatly affect the overall throughput and latency performance of the system. This paper presents a series of network-on-chip transaction-level model (TLM) algorithms that provide a highly abstracted view of the process of data transmission in priority preemptive and non-preemptive networks-on-chip, which permit a major reduction in simulation event count. These simulation models are tested using two realistic application case studies and with synthetic traffic. Results presented demonstrate that these lightweight TLM simulation models can produce latency figures accurate to within mere flits for the majority of flows, and more than 93% accurate link dynamic power consumption modelling, while simulating 2.5 to 3 orders of magnitude faster when compared to a cycle-accurate model of the same interconnect

An Interactive System Level Simulation Environment for Systems- on-Chip

International audienceThis article presents an interactive simulation environment for high level models intended for Design Space Exploration of Systems-On-Chip. The existing open source development environment TTool supports the MARTE compliant UML profile DIPLODOCUS and enables the designer to create, simulate and formally verify models. The goal is to obtain first performance estimations of the system intended for design while minimizing the modeling effort. The contribution outlined in this paper is an additional module providing means for controlling the simulation in real time by performing step wise execution, saving and restoring simulation states as well as animating UML models of the system. Moreover the paper elaborates on the integration of these new features into the existing framework consisting of a simulation engine on the one hand and a graphical user interface on the other hand