MIPS vs ARM vs X86 vs NPU: Which Hardware Rules for IoT Gateways?

Introduction

An Internet of Things (IoT) gateway is a physical device or software program that serves as the connection point between sensors, devices and controllers in the field (known as nodes) and the cloud or other networks. IoT gateways facilitate communication, data flow and analysis between devices.

The hardware platform of an IoT gateway is a crucial choice that impacts performance, power consumption, cost, software compatibility and more. There are four major hardware architectures to consider for IoT gateways: MIPS, ARM, X86 and NPUs (Neural Processing Units).

Selecting the right platform depends on factors like processing requirements, power constraints, ecosystem support and use cases. This article provides an in-depth comparison of MIPS, ARM, X86 and NPU platforms for IoT gateways to help you determine the best option for your needs.

MIPS

MIPS (Microprocessor without Interlocked Pipeline Stages) is a RISC (reduced instruction set computer) instruction set architecture developed by MIPS Technologies. It was one of the earliest commercial RISC architectures and has been used in embedded systems like routers, gateways and other network devices.

Strengths of MIPS for IoT Gateways

  • Performance efficiency – The RISC architecture and pipelining allows MIPS cores to perform more instructions per clock cycle, providing high performance even at lower clock speeds. This makes it energy and cost efficient.
  • Real-time capabilities – MIPS has architectural features like branch delay slots that allow deterministic execution times for real-time applications.
  • Scalability – MIPS supports multiple cores and threading for flexible scaling. The architecture has proven scalable up to 128 cores.
  • Software maturity – MIPS has decades of software support with mature operating systems like Linux, real-time operating systems and development tools.

Weaknesses of MIPS for IoT Gateways

  • Complex instruction set – While RISC, MIPS has a larger instruction set than rivals like ARM which increases memory footprint.
  • Lacks native memory management – No memory protection or virtual memory capabilities, requiring OS support.
  • Not widely used in IoT endpoint devices – While popular in infrastructure, MIPS lacks traction in endpoint IoT devices versus ARM.

Popular MIPS-based IoT Gateways

  • Linksys WRT1900ACS – A consumer wireless router using a 1.6 GHz dual-core MIPS CPU.
  • Alotcer AR7091 – An industrial IoT router with 600 MHz MIPS CPU.
  • Juniper SRX Series – Secure router series with high-performance multi-core MIPS CPUs.
  • Cavium OCTEON – A family of multi-core MIPS64 processors targeting wired and wireless infrastructure.

ARM

ARM refers to the instruction set architecture and related RISC CPUs designed by ARM Holdings. ARM cores power the majority of smartphones and tablets and are widely used in embedded systems.

Strengths of ARM for IoT Gateways

  • Low power consumption – ARM processors are designed for power efficiency to enable battery-powered devices. This suits low-power IoT endpoints.
  • Small silicon footprint – ARM cores have compact silicon die sizes translating to low chip costs. A major benefit for price-sensitive IoT.
  • Ecosystem support – As the dominant mobile processor, ARM benefits from strong ecosystem support and available software stacks.
  • Scalability – ARM supports multiple cores and architectures scaling from tiny microcontrollers to application processors.

Weaknesses of ARM for IoT Gateways

  • No native support for virtual memory – ARM lacks full virtual memory capabilities relying on OSes like Linux.
  • Real-time performance not as strong – While improving, real-time performance lags behind MIPS. RTOS support helps.
  • Lower single thread performance – More RISC-like pipeline means ARM lags in single thread processing versus MIPS and X86.

Popular ARM-based IoT Gateways

  • Raspberry Pi – This hugely popular single board computer uses ARM CPUs. Often used for DIY gateways.
  • Beaglebone – Open source hardware single board computers using TI ARM processors.
  • Alotcer AR7091G – Multi-core ARM Cortex-A9 processor tailored for industrial IoT gateways.
  • Qualcomm FSM90xx – Snapdragon IoT modem platform with integrated ARM application processor.

X86

The x86 architecture from Intel and AMD dominates notebooks, desktops and servers with high performance across single and multi-threaded workloads.

Strengths of X86 for IoT Gateways

  • Processing performance – X86 excels at raw CPU performance for data and network intensive gateways.
  • Powerful cores – Modern 64-bit x86 cores support advanced virtualization, memory protection and multi-threading.
  • Software compatibility – X86 binaries run on most operating systems without porting simplifying development.
  • Virtualization support – Hardware virtualization capabilities ideal for multi-tenant gateways.

Weaknesses of X86 for IoT Gateways

  • High power consumption – Performance comes at a cost with high thermal design power unsuitable for battery or low energy use.
  • Large silicon footprint – Complex x86 cores take up more die area raising costs over RISC architectures.
  • Overkill for simpler gateways – Powerful x86 can be overprovisioned when deployment requires a low-cost, low-power gateway.

Popular X86-based IoT Gateways

  • Intel Atom E3800 – Low power x86 SoCs for embedded IoT gateways.
  • Intel Xeon D – Server-class processor giving high performance for demanding gateways.
  • Jetway NF9D-2780 – Atom-based embedded box for industrial IoT.
  • ADLINK IXG-100 – Rugged x86 gateway including virtualization features.

NPUs

A Neural Processing Unit (NPU) is a processor tailored to machine learning workloads. NPUs accelerate tasks like neural network inferencing while being more power efficient than repurposing GPUs or FPGAs.

Strengths of NPUs for IoT Gateways

  • Inferencing acceleration – NPUs speed up ML inferencing, ideal for image and speech processing at the edge.
  • Low power – Designed to provide high TOPS/Watt (Trillions of Operations Per Second per Watt) for edge inferencing.
  • Hardware acceleration – Offload ML inferencing from the main application processor for greater efficiency.
  • Optimized for neural networks – Unlike GPUs, NPUs designed specifically for neural network models.

Weaknesses of NPUs for IoT Gateways

  • Narrow focus – NPUs lack the general programmability of CPUs or flexibility of GPUs. Current NPUs are ML inferencing accelerators.
  • Still maturing technology – NPU capabilities and software support still evolving compared to established CPUs and GPUs.
  • Model portability challenges – Model quantization and other optimizations needed to take advantage of NPU execution.

Popular NPU-based IoT Gateways

  • Intel Movidius – Dedicated vision processing unit adds neural inferencing to gateways.
  • NVIDIA Jetson Xavier – Combines ARM CPU with Tensor Core NPU for edge AI.
  • Google Edge TPU – ASIC accelerator designed to run TensorFlow Lite ML models.
  • Xnor.ai AI2GO – Low-power edge device with integrated binary neural network NPU.

Comparison of the Four Platforms

MIPS vs ARM

  • MIPS has higher single-threaded performance while ARM excels at low power multi-core designs.
  • MIPS has strong real-time capabilities while ARM supports a broader ecosystem including endpoint devices.
  • MIPS powers high-performance wired gateways while ARM dominates in the battery-powered endpoint space.

MIPS vs X86

  • X86 provides a much higher level of performance at the cost of greater power demands.
  • MIPS offers real-time responsiveness and deterministic behavior not found in X86.
  • X86 supports advanced virtualization and memory management lacking in MIPS.

MIPS vs NPU

  • MIPS is a general purpose CPU while NPUs accelerate a narrow range of ML inferencing workloads.
  • MIPS can handle overall gateway system control and networking functionality beyond NPU’s specialty.
  • NPUs complement a MIPS system by offloading neural networks leaving MIPS to handle the OS and remaining tasks.

ARM vs X86

ARM vs X86

  • ARM emphasizes power efficiency which X86 is less focused on. ARM excels in low power endpoint devices.
  • X86 provides significantly higher CPU performance but has large power and cost drawbacks.
  • ARM relies on OS virtualization while X86 has robust hardware virtualization capabilities.

ARM vs NPU

  • As with MIPS, ARM provides general computation capabilities that NPUs lack.
  • For AI-enabled gateways, ARM + NPU combines software flexibility with ML acceleration.
  • ARM’s strength in low power endpoints complements the high efficiency of NPU silicon.

X86 vs NPU

  • X86 is a fully programmable CPU while NPUs just accelerate neural network inferencing.
  • NPUs can offload ML tasks from X86 at lower power suitable for edge gateways.
  • X86 overall performance much higher but NPUs better optimized for AI edge workloads.

Factors to Consider When Choosing a Hardware Platform

Selecting the right hardware platform involves weighing a number of considerations:

Performance Requirements

  • The processing demands of target workloads impacts choice of MIPS, ARM, X86 or NPU architecture.
  • Data and network intensive workloads may need the high performance of X86.
  • MIPS, ARM and NPUs also provide various performance options suitable for many gateways.

Power Consumption Constraints

  • Battery-powered or low energy gateways favor ARM efficiency or add dedicated NPU processors.
  • MIPS provides performance at modest power levels.
  • X86 is the least power efficient architecture.

Cost

  • MIPS and ARM have cost advantages for simpler gateways given their smaller silicon size.
  • X86 provides performance but at higher silicon and system costs.
  • Adding dedicated NPU silicon increases costs but can optimize total power.

Software Compatibility

  • X86 allows reuse of software assets like VMs and containers developed for servers.
  • MIPS and ARM may require some software porting and optimization.

Ecosystem Support

  • X86 benefits from extensive general purpose ecosystem support.
  • ARM has robust mobile and embedded device support.
  • MIPS and NPUs have less extensive support currently.

Case Studies

Smart Camera with AI Processing

For a battery-powered smart camera leveraging machine learning for image analysis, an ARM + NPU combination makes sense. ARM provides a low power application processor handling general system tasks while the NPU accelerates neural network inferencing efficiently.

Industrial Asset Monitoring Gateway

An industrial IoT gateway for real-time asset monitoring would benefit strongly from MIPS architecture. MIPS provides excellent real-time performance for industrial control while maintaining efficiency for modest workloads.

Multi-Tenant Edge Gateway

A multi-tenant edge gateway supporting multiple virtual tenants requires strong virtualization capabilities. An x86 platform would be ideal here, leveraging hardware assisted virtualization and performance for isolating workloads.

Smart Home Hub

In cost-sensitive consumer IoT, choosing an inexpensive but capable platform is key. An ARM Cortex-M microcontroller provides enough performance for a smart home hub at very low cost and power.

Frequently Asked Questions

What is the difference between a microcontroller and a microprocessor?

  • Microcontrollers like Cortex-M integrate processor cores with peripherals like memory, I/O, timers etc. into a single chip. Microprocessors are just the processor/CPU itself.

What is a system-on-a-chip (SoC)?

  • A SoC integrates an entire computer system into a single chip. SoCs contain microprocessor cores plus additional components like memory, storage, I/O, modems and more.

What is the difference between 32-bit and 64-bit architectures?

  • 32-bit can only process 32 bits of data per instruction while 64-bit can process 64 bit data widths for higher performance. 64-bit also enables larger memory addressing capabilities.

What is the role of an operating system in an IoT gateway?

  • The OS manages hardware resources, schedules tasks, provides services like networking stacks and file systems, implements security features and enables developing high-level applications.

What are some popular IoT gateway operating systems?

  • Linux and Linux-based distributions like Ubuntu are popular open source choices. Real-time operating systems like FreeRTOS are also widely used. Microsoft Azure Sphere OS brings security focus.

What are some security considerations for IoT gateways?

  • Secure boot, trusted execution environments, crypto acceleration, and central management are key for securing both the gateway and connected devices.

Conclusion

Choosing the right hardware architecture for an IoT gateway involves balancing trade-offs between performance, power, cost, ecosystem support and use case requirements.

MIPS provides a strong combination of real-time responsiveness, power efficiency and software maturity at moderate cost. It excels in wired industrial gateway products.

ARM‘s popularity in embedded and mobile gives it a robust ecosystem for low cost and low power gateways, especially battery-powered endpoint devices.

X86 delivers excellent performance and virtualization capabilities for demanding gateways, but has high power and cost disadvantages.

NPUs are an emerging technology that can accelerate machine learning inferencing as a complement to conventional CPU architectures in AI-enabled gateways.

By understanding the core strengths and weaknesses of these platforms, IoT product designers can select the right hardware foundations for their specific performance, cost and use case needs as they architect the next generation of intelligent gateways.