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PHYSICAL Layer: 3GPP and IEEE

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Physical Layer Modifications in Modern Wireless Standards Physical Layer Modifications in Modern Wireless Standards A Comprehensive Tutorial on IEEE and 3GPP Physical Layer Evolution Introduction to the Physical Layer The **Physical (PHY) Layer** is the foundation of any wireless communication system. It is responsible for the actual transmission and reception of raw data over the air. Its functions include converting digital data into analog signals, modulating them onto a carrier frequency, and managing the radio frequency (RF) hardware. The evolution of the PHY layer is what drives improvements in speed, reliability, and spectrum efficiency in modern standards like Wi-Fi 6/7 and 5G. Physical Layer Block Diagram This diagram illustrates the key functions of a wireless...
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MAC Layer: 3GPP and IEEE

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MAC Layer Modifications in Modern Wireless Standards MAC Layer Modifications in Modern Wireless Standards A Comprehensive Tutorial on IEEE and 3GPP MAC Layer Evolution Introduction to the MAC Layer The **Media Access Control (MAC)** layer sits directly on top of the physical layer in a wireless communication system. Its primary role is to manage and control access to the shared wireless channel. It decides which device gets to transmit, when it transmits, and for how long. Essentially, it's the "traffic cop" of the wireless network. The evolution of MAC layer protocols is critical for improving network capacity, reducing latency, and enabling new use cases in modern standards like Wi-Fi 6/7 and 5G. MAC Layer Block Diagram Here is a simplified text-...
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MIMO Signal Estimation and Detection

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MIMO Signal Detection Tutorial MIMO Signal Detection Tutorial A guide to understanding the fundamental concepts and algorithms. Introduction to MIMO Detection In a Multiple-Input Multiple-Output (MIMO) wireless communication system, multiple data streams are transmitted simultaneously from different antennas. These streams get mixed up as they travel through the wireless channel. The job of a MIMO signal detector at the receiver is to unscramble these mixed signals and accurately recover the original data streams. This is the final and most crucial step in the communication chain. 1. Channel Estimation: The Prerequisite Before any of the detection algorithms can work, the receiver needs an accurate estimate of the channel matrix \(H\). This process is kn...
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Coding Theory (Error Detection and Error Correction)

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Error Detection and Correction Techniques Error Detection and Correction Techniques Introduction Error detection and correction are essential in digital communications and storage systems to ensure data integrity. Errors can occur due to noise, interference, or hardware malfunctions. Basic Concepts Error Detection: Identifying whether errors have occurred in transmitted data Error Correction: Identifying and correcting errors in transmitted data Redundancy: Adding extra bits to detect or correct errors Forward Error Correction (FEC): Ability to correct errors without retransmission Common Techniques 1. Parity Check The simplest form of error detection that uses a single parity bit. Types: Even Parity: Parity bit makes total number of 1s even Odd Parity: Parity bit makes total number of 1s odd Even Par...
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Digital Signal Processing

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DSP for Wireless Domain - Interview Preparation (Enhanced) Digital Signal Processing (DSP) for Wireless Domain - Interview Preparation (Enhanced) This document summarizes key DSP concepts, including examples, mathematical equations, and text-based block diagrams, tailored for a DSP engineer position interview in the wireless domain. 1. Fundamentals of Signal Conversion (Analog to Digital) Wireless signals are inherently analog and continuous. DSP involves converting these to digital for processing. Sampling The process of converting a continuous-time signal \(x(t)\) into a discrete-time signal \(x[n]\) by taking its amplitude measurements at regular intervals, where \(x[n] = x(nT_s)\) and \(T_s\) is the sampling period. The sampling rate is \(F_s = 1/T_s\). Nyquist-Shannon Sampling Theorem: To perfectly reconstruct an analog...
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Channel Equalization

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Channel Equalization Tutorial Channel Equalization Tutorial 1. Introduction to Channel Impairments In digital communication systems, signals often travel through various physical media (e.g., copper wires, optical fibers, wireless channels). These channels are rarely ideal and introduce distortions that can severely degrade the quality of the received signal. These distortions are generally referred to as channel impairments . Key impairments include: Noise: Unwanted random fluctuations added to the signal (e.g., thermal noise, shot noise, interference). Inter-symbol Interference (ISI): This is a primary concern. ISI occurs when the spreading of a pulse for one symbol overlaps with subsequent symbols, causing a "smearing" effect and making it difficult to distinguish individual symbols. This is typically caused by multipath propagation or the frequency-selective natur...
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