Today's virtual prototypes model complex manycore platforms. In application domains such as network processing, they may comprise hundreds of processors, which makes simulation speed the key issue due to the single-threaded execution semantics of SystemC. We propose CoMix, the Concurrent Model Interface, for the distributed simulation of large-scale SystemC models. CoMix provides robust communication between peers, enables their loose synchronization, and manages the overall life cycle. It is an overlay technology neither requiring modified simulators nor depending on a hosts' communication infrastructure. The CoMix library is small (2k Lines of Code) and easily deployable. We quantify its overhead on synthetic benchmarks and observe reasonable speedups for synthetic benchmarks and a large real-world example, e.g., 3.3X and 4X for a 4-peer simulation.

For ad-hoc home networks without central coordinator, IEEE 802.11 systems merely support service differentiation. In many usage scenarios of a typical home network with applications requiring a strict quality of service (QoS), this MAC functionality is not sufficient. In order to counteract this problem, we developed in previous works a modified MAC scheme based on the IEEE 802.11 enhanced distributed channel access (EDCA) function. This paper describes enhancements of the modified MAC scheme enforcing prioritized medium access for strict QoS applications. For the first time, the established concept is realized in a distributed way with in-band signaling. Our enhanced MAC is embedded into a comprehensive IEEE 802.11n reference application to demonstrate its effectiveness in combination with the latest amendments like frame aggregation. The reference application is modeled in SystemClick, a framework for describing and evaluating packet processing applications on resource constraint network nodes. This enables functional validation and provides a path to future, cost-efficient implementations on programmable devices. On this basis, the paper presents simulation results substantiating the significant improvement of QoS parameters like delay and throughput. Besides enforcing strict priorities, collisions can be reduced to zero and the average waiting time can be decreased by up to 33 % for typical usage scenarios.

Wireless network (WLAN) platforms today are based on complex and inflexible hardware solutions to meet performance and deadline constraints for media access control (MAC). Contrary to that, physical layer solutions, such as software defined radio, become more and more flexible and support several competing standards. A flexible MAC counterpart is needed for system solutions that can keep up with the rising variety of WLAN protocols. We revisit the case for programmable MAC implementations looking at recent WLAN standards and show the feasibility of a software-based MAC. Our exploration uses IEEE 802.11a-e as design driver, which makes great demands on Quality-of-Service, security, and throughput. We apply our SystemC framework for efficiently assessing the quality of design points and reveal trade-offs between memory requirements, core performance, application-specific optimizations, and responsiveness of MAC implementations. In the end, two embedded cores at moderate speed (< 200 MHz) with lightweight support for message passing using small buffers are sufficient for sustaining worst-case scenarios in software.

Designing efficient yet flexible medium access controllers (MAC) for wireless protocols is a challenge. Not only are these protocols still evolving, they are also increasingly demanding in terms of throughput and real-time requirements. In order to support a careful application-driven architecture development, reference applications are required that expose the full system and enable the quantitative evaluation of performance-flexibility tradeoffs. For this purpose, we have captured the 802.11n MAC protocol in an executable reference application which comprises the system function and its environment including traffic scenarios. We model the reference in Click, a packet processing framework. The functionally-correct model captures performance-relevant aspects such as the wireless protocol timing exactly. Leveraging extensions to Click we can use the model for the development and deployment of embedded architectures. Our 802.11n MAC model comprises between 118 and 1238 functional elements and can be simulated in real time depending on the scenario. Due to its modularity, additional scenarios can be added productively.

A wireless network (WLAN) provides unique challenges to system design. A WLAN uses a shared and highly unreliable medium, where protocols must rely on precise timing of requests and responses to detect submission errors and priorities among network nodes. In addition, WLAN stations are often embedded and have tight constraints on power, costs, and performance. To design WLAN nodes, precise estimations on performance and resource usage are needed for the complete network system to explore the design space and assess the quality of solutions. Our SystemClick framework combines SystemC with resource models and performance annotations derived from actual implementations based on Click. Model generation is automated, and the performance of a SystemClick model is obtained depending on actual activation patterns of different functional blocks in the model. A 802.11 a/b/g/e case study demonstrates our approach for the analysis of real-time critical systems.

Within the field of automation technology the use of Industrial Ethernet is rising. This in turn demands devices capable of precisely recording, analyzing, and manipulating communication data for diagnostic purposes. Existing solutions so far lack required flexibility or are unable to cope with sustained Gigabit-per-second data streams. This is especially true for general-purpose approaches employing ordinary network adapters and plain software-based analysis.In this paper we describe a flexible and lightweight network agent for real-time, high-performance networks. This agent is capable of handling sustained data rates up to 2x 1GBit/s while offering real-time event-triggers, 10ns-resolution timestamps, real-time filtering, and statistics functions. An auxiliary processing unit as well as a modular software environment allow customization for a variety of tasks. The agent is realized as a dual processor SoC design on a Xilinx Virtex-II Pro FPGA.