DOCSEARCHbyAlgolia
Submit Docs

leozzmc Technical Notes

website·Indexed 30 days ago

https://leozzmc.github.io

A collection of technical study notes and tutorials covering LeetCode problem solutions in C++, AWS services (IoT Core, S3 Gateway Endpoints, SQS, FreeRTOS), Linux OS concepts (PID 0, Buffer Overflow), and hardware projects like SatNOGS.

Tokens
191.6K
Snippets
546
Records
1.1K
Agent score
75%

What's inside leozzmc

  1. Introduction to Federated Learning and Parallel Computing

    Federated Learning is designed to train models on data residing on user devices to address privacy concerns, especially in medical environments or regions with strict privacy laws (e.g., Europe and US), where users refuse to upload sensitive data to a centralized server. It builds upon the foundations of parallel computing and distributed machine learning to reduce the time cost of training large models with massive parameters by distributing the computation across multiple GPUs (e.g., using 20 GPUs to achieve the work of one GPU running for a year).

  2. Overview of Delay-Tolerant Networking (DTN) vs Traditional Internet

    Delay-Tolerant Networking (DTN) is designed for space environments where traditional TCP/IP fails due to high latency, intermittent connectivity, and frequent disruptions. Unlike the traditional Internet, which views disconnection as a failure and requires a continuous end-to-end path, DTN treats disruption as a normal state and uses a 'Store-Carry-Forward' mechanism. It shifts from a session-oriented communication model to a message/object-oriented one, where routing is based on a dynamic topology that includes a time axis.

  3. Introduction to Meshtastic Open Source Project

    Meshtastic is an open-source project based on LoRa (Long Range) wireless communication technology. It enables low-power, long-distance wireless signal transmission using the LoRa protocol without relying on existing cellular infrastructure. It is particularly suitable for emergency backup communication systems or mountain rescue operations.

  4. Overview of SatNOGS Ground Station Architecture

    SatNOGS (Satellite Networked Open Ground Station) is a global network used to track, receive, and upload satellite observation data. Its architecture consists of three primary components:

    1. SatNOGS Network: Handles scheduling, task allocation, and result collection.
    2. SatNOGS Client: Local software that controls the Software Defined Radio (SDR), rotator, and recording process.
    3. SatNOGS DB: A database containing satellite metadata such as frequencies, modulation schemes, and Two-Line Element (TLE) orbital data.

  5. Overview of NFV Deployment and Traffic Scheduling Optimization

    Network Function Virtualization (NFV) decouples network functions from physical infrastructure, allowing Virtual Network Functions (VNFs) to run on general-purpose COTS servers. This flexibility introduces challenges in deploying VNFs across different geographical locations and scheduling network traffic between data centers. The goal is to minimize both deployment costs (resource consumption like CPU, memory, storage) and communication costs (e.g., point-to-point latency). The problem is formulated as a Mixed-Integer Linear Programming (MILP) problem and solved using a relaxation-based algorithm to reduce computational complexity.

  6. Overview of AWS Lambda Function URLs

    A Lambda Function URL is a dedicated HTTP(S) endpoint for a Lambda function. Once created, the URL endpoint remains permanent. The standard format for these endpoints is https://<url-id>.lambda-url.<region>.on.aws. Note that some AWS regions may not support Function URLs; in such cases, using API Gateway with Lambda Integration is the alternative.

  7. Overview of NASA HDTN Core Architecture

    High-rate Delay-Tolerant Networking (HDTN) implements a 'Store-Carry-Forward' mechanism to ensure data delivery in environments where continuous network connectivity is not guaranteed. The architecture consists of the following core components:

    • Bundle: The fundamental unit of data that can be transmitted across time and nodes.
    • Ingress: Receives Bundles and determines if they should be forwarded immediately.
    • Storage: Temporarily buffers Bundles when communication links are unavailable.
    • Contact Plan: A schedule describing future available communication windows.
    • Scheduler / Router: Manages link states and calculates the next hop for data.
    • Egress: Delivers the Bundle to the correct output duct.
    • Convergence Layer: Adapts Bundles to run over actual physical transport protocols.
    • ZeroMQ Events: Synchronizes state changes during link anomalies or schedule updates.

  8. Overview of C++ Standard Template Library (STL) for Competitive Programming

    The C++ Standard Template Library (STL) is a collection of containers that implement various data structures using C++ Templates. Templates allow a structure to be defined once and used with different data types (e.g., int, float, char). The STL consists of six primary components: Containers, Algorithms, Iterators, Function objects, Adaptors, and Allocators. For problem-solving (such as LeetCode), the most critical components to focus on are Containers, Iterators, and Algorithms.

  9. Overview of SatNOGS Architecture

    SatNOGS (Satellite Networked Open Ground Station) is a global network for automating satellite signal tracking and reception. The architecture consists of three main components:

    1. SatNOGS Network: Handles scheduling, task allocation, and observation database management based on TLE (Two-Line Element set) data.
    2. SatNOGS Client: A local Linux-based controller that manages the SDR, rotator, and recording. It performs Doppler correction and generates waterfall plots.
    3. SatNOGS DB: A database containing satellite frequencies, modulation types, and TLEs used to calculate Azimuth and Elevation for antenna tracking.

  10. Overview of Meshtastic

    Meshtastic is an open-source project based on LoRa (Long Range) wireless communication technology. It enables low-power, long-distance wireless signal transmission without relying on existing cellular infrastructure, making it ideal for emergency backup communication or mountain rescue operations. It operates as a mesh network where messages are relayed from one node to another until they reach the destination.

  11. Overview of 5G System (5GS) Security Architecture

    The 5G System (5GS) consists of the Access Network, Core Network, and User Equipment (UE). It utilizes a Service-Based Architecture (SBA) where Network Functions (NFs) interact via Service-based Interfaces (SBI). Key components for security and policy include:

    • Policy Control Function (PCF): Provides a unified framework for defining policies. Historically used for QoS and charging, it is now being extended for security policies.
    • Network Data Analytics Function (NWDAF): Provides network data analytics including load levels, service experience, network performance, and anomaly detection. The PCF can subscribe to NWDAF notifications to dynamically update policies.
    • User Plane (UP) Security Enforcement: Currently based on whether confidentiality and integrity algorithms are enabled on the air interface between the UE and the base station. Integrity protection is optionally enabled (e.g., per slice).

  12. Overview of AWS IoT Fleet Provisioning methods

    Fleet Provisioning allows for large-scale device onboarding in AWS IoT Core via two primary methods:

    1. Provisioning by Claim: Devices are manufactured with embedded 'claim certificates' and private keys. Upon first connection, AWS IoT exchanges these temporary claim certificates for a unique, permanent device certificate.
    2. Provisioning by Trusted User: Devices are connected to AWS IoT when a trusted entity (e.g., an end-user or technician) sets them up using a mobile application at the deployment location.