5G RAN Technology Practice Exams

This JSON object contains 250 flashcards in Question and Answer format based on the 5G RAN Technology lecture transcript, adhering to specific LaTeX formatting for all mathematical and scientific expressions.

What was the primary service of 1G cellular networks in the 1980s?

Analog Voice Services (car telephony)

Which cellular generation introduced digital voice services and SMS in the 1990s?

2G

What integration occurred during the 2000s with 3G technology?

Integration of data services (mobile web) including circuit switched voice and packet switched data

What are the primary characteristics of 4G networks of the 2010s?

Everything IP based with higher data rates for voice, email, web, and audio/video streaming

What are the core focuses of 5G networks in the 2020s?

Control and Management for IoT, Tactile Internet, and ML/AI

What is the peak data rate goal for 5G networks?

Multi-gigabit per second peak data rates, specifically $> 10\,Gbps$

What are the three main service categories for 5G deployment scenarios?

Massive Internet of Things, Mission-critical control, and Enhanced mobile broadband

What is the target radio latency for 5G critical machine communication?

$$< 1\,ms$$

How many times more traffic is 5G designed to handle compared to legacy networks?

$$10,000\times$$

What is the battery life goal for 5G Massive Machine Communication?

$$10\,Years$$

What is the target node density for 5G Massive IoT?

$1\,million$ nodes per $km^2$

What is the data capacity target for 5G Enhanced mobile broadband?

$10\,Tbps$ per $km^2$

What are the frequency ranges for low-band, mid-band, and high-band spectrum in 5G?

Low-band is $700\,MHz$, Mid-band is $3.5\,GHz$, and High-band (mmWave) is $28\,GHz$

What does the 5G Radio Access Network (RAN) comprise?

Antennas, radios, and processing units for radio communication

What is the role of the 5G Core Network (5GC)?

Network infrastructure with switches, routers, and servers supporting software-based Network Functions (NF)

What are the three major deployment units in a 5G network?

User Equipment (UE), base station (gNodeB), and Core Network

What does URLLC stand for in the context of 5G?

Ultra-reliable low-latency communication

What characterizes Non-Standalone Access (NSA) in 5G?

It uses a 4G core network where control signaling is sent through a radio Master Node (MN)

What is the defining feature of Standalone Access (SA) in 5G architecture?

A completely new core service-based architecture where each radio node is autonomously controlled by the 5G core

What is a 5G CPE (Customer Premise Equipment)?

A 5G-enabled or fixed wireless access (FWA) device that converts mobile signals into Wi-Fi or Ethernet signals

What are the main components of a 5G RAN?

Base stations (gNodeB), remote radio units (RRU), and antenna systems

Name three transport methods used in high-capacity 5G backbone networks.

Fiber, Microwave, and MEC (Multi-access Edge Computing)

What are the three core functional components mentioned for 5G RAN hardware?

Radio Unit, Baseband Processing, and Antenna

What does the Integrated Access and Backhaul (IAB) standard provide in 5G?

It allows gNBs to provide both user access and backhaul connectivity wirelessly

In 3GPP specifications, what technology family is assigned the number series '38'?

5G NR (New Radio)

What was the 3GPP specification number series for 4G LTE?

36

What was the 3GPP specification number series for 3G (UMTS)?

25

What was the 3GPP specification number series for GSM/EDGE?

45

What is the role of the gNodeB (gNB) in a 5G network?

It is the primary access point that connects User Equipment (UE) to the core network and manages radio resources, mobility, and security

Define the AMF (Access and Mobility Management Function) in the 5G Core.

Handles mobility management, connection management, and access authentication/security

What is the primary responsibility of the SMF (Session Management Function)?

Manages session establishment, termination, and UE IP address allocation

What is the function of the UPF (User Plane Function)?

Handles data forwarding between the RAN and external networks, packet inspection, and QoS handling

What happens in Access Stratum (AS) signaling?

It handles the radio interface between the UE and the RAN for radio resource management and mobility

What is the responsibility of Non-Access Stratum (NAS) signaling?

It manages communication between the UE and the core network for registration, authentication, and session setup

In 5G SBA, what does PCF stand for and what is its role?

Policy Control Function; it supports a unified policy framework to govern network behavior

What does NRF (Network Repository Function) do?

Supports service discovery by maintaining NF profiles of available instances and their supported services

What is the role of UDM (Unified Data Management)?

Generates 3GPP AKA authentication credentials, handles identification, and manages subscriptions

What is the function of the AUSF (Authentication Server Function)?

Supports authentication for 3GPP access and untrusted non-3GPP access

What is the role of the NEF (Network Exposure Function)?

Exposes capabilities and events and translates internal-external information securely

What is the purpose of the NSSF (Network Slice Selection Function)?

Selects the set of Network Slice instances serving the UE

What is the role of the Application Function (AF)?

Interacts with the Core Network to support application influence on traffic routing and interact with policy frameworks

What does the Remote Radio Head (RRH) do in basic RAN architecture?

Converts digital information into radio signals and ensures correct frequency bands and power levels

What function do Baseband Units (BBU) perform?

Signal-processing functions including error detection, signal securing, and effective resource usage

Describe the signal path from the Core to the UE in a RAN.

The BBU receives digital signals from the core, sends them to the RRH via fiber, and the RRH converts them to RF for antenna transmission

What are the responsibilities of the MAC layer in the RAN protocol stack?

Resource allocation, scheduling, HARQ error correction, and multiplexing data

What are the responsibilities of the RLC layer in the RAN protocol stack?

Data transfer, error correction, segmentation, reassembly, in-sequence delivery, and duplicate detection

Define Traditional RAN.

A configuration where all equipment (antenna, radio, baseband) is at the tower site with tightly coupled proprietary hardware and software

Define Centralized RAN (C-RAN).

Baseband processing units are moved to a central BBU pool, and towers only contain antennas and radios

Define Virtualized RAN (vRAN).

Baseband functions run on cloud or virtual servers instead of legacy physical hardware

Define Open RAN (O-RAN).

A RAN based on open standards allowing equipment from different vendors to interoperate

What is 5G New Radio (NR)?

The radio access technology (RAT) and air interface standard developed by 3GPP for 5G

What advanced technology does 5G NR use to focus radio signals for improved efficiency?

Beamforming

What frequency range defines FR1 in 5G NR?

$$410\,MHz - 7125\,MHz$$

What frequency range defines FR2 in 5G NR?

$$24250\,MHz - 52600\,MHz$$

What names were previously used for FR1 and FR2 respectively?

Sub-6 GHz and mmWave

What subcarrier spacing (SCS) values are used in FR1?

$15$, $30$, and $60\,kHz$

What subcarrier spacing (SCS) values are used in FR2?

$60$, $120$, $240$, $480$, and $960\,kHz$

What is the maximum IFFT size in 5G NR?

$$4096$$

What is the formula for subcarrier spacing ($\Delta f$) based on the parameter $\mu$?

$$\Delta f = 2^{\mu} \times 15\,kHz$$

Which multiplexing technique is used for 5G NR downlink?

OFDMA

Which multiplexing technique is used for 5G NR uplink?

OFDMA and DFT-precoded OFDM (SC-FDMA)

How does SC-FDMA differ from OFDMA?

SC-FDMA uses a single carrier and distributes information across subcarriers after DFT pre-coding for lower PAPR

What is 'Flexible Numerology' in 5G?

A technique allowing multiple mobile users to share spectrum effectively using different subcarrier spacings

What is the relationship between SCS and symbol duration?

Symbol duration is inversely proportional to SCS ($Symbol\,Duration \propto 1/SCS$)

What is the useful symbol time ($T_u$) for a $15\,kHz$ subcarrier spacing?

$$66.7\,\mu s$$

What is the cyclic prefix ($T_{cp}$) for a $15\,kHz$ subcarrier spacing?

$$4.7\,\mu s$$

What is the useful symbol time for a $960\,kHz$ subcarrier spacing?

$$1.05\,\mu s$$

What is the duration of one 5G NR frame?

$$10\,ms$$

What is the duration of one 5G NR subframe?

$$1\,ms$$

How many symbols are in one standard 5G NR slot?

$$14\,symbols$$

How many subframes are in a half-frame?

$$5\,subframes$$

What is the slot duration for an SCS of $15\,kHz$ ($\mu=0$)?

$$1\,ms$$

What is the slot duration for an SCS of $120\,kHz$ ($\mu=3$)?

$$0.125\,ms$$

What defines 'Numerology' in 5G?

The configuration of waveform parameters including subcarrier spacing, symbol time, and cyclic prefix size

What is the purpose of the Cyclic Prefix (CP)?

To avoid interference between symbols by inserting a replica at the start of each symbol

In which numerology ($\mu$) can an 'extended cyclic prefix' be applied?

$\mu = 2$ (60 kHz SCS)

How many symbols are in a slot using the extended cyclic prefix?

$$12\,symbols$$

Which duplex mode do all FR2 bands use?

TDD (Time Division Duplexing)

What is Frequency Division Duplexing (FDD)?

Simultaneous uplink and downlink transmissions using different frequencies separated by a guard band

What is Time Division Duplexing (TDD)?

Sharing the same frequency band between uplink and downlink transmissions by occurring at different times

What is Supplementary Uplink (SUL) mode?

An additional lower-frequency band configured solely for the uplink to improve range and performance at the cell edge

Which duplex mode uses spatial diversity where one part of radiating elements transmits while the other receives simultaneously?

Full Duplex (FD)

Can a mobile device transmit on both TDD and SUL bands simultaneously?

No

What are RNTIs (Radio Network Temporary Identifiers) used for?

To identify and differentiate UEs, specific radio channels, or groups of UEs within a cell

What does RA-RNTI stand for and when is it used?

Random Access RNTI; used to identify the UE during the random access procedure

What is the purpose of the C-RNTI?

It is allocated to an RRC-connected UE for general communication within a cell

What is the P-RNTI used for?

Paging and System Information change notification

What is the hex value of P-RNTI?

$$FFFE$$

What is the hex value of SI-RNTI?

$$FFFF$$

What is the SI-RNTI used for?

Broadcast of System Information messages

What is the Temporary C-RNTI used for during contention resolution?

Used when no valid C-RNTI is available for Msg3 transmission and resolution

What information does the TPC-RNTI provide?

Transmit Power Control information for traffic and uplink control channels

What does HARQ stand for?

Hybrid Automatic Repeat Request

What two components make up HARQ?

Forward Error Correction (FEC) and Automatic Repeat Request (ARQ)

What is 'Soft Combining' in the context of HARQ?

A technique where bad packets are stored in a buffer and combined with retransmissions rather than discarded

What occurs during Chase Combining (CC)?

The gNB resends the same identical packet data, and the UE combines it with the stored original to improve SNR

What is the Primary Synchronization Signal (PSS) used for in 5G NR?

Helps UEs detect the presence of a cell, provides symbol timing, and determines physical layer cell identity ($N_{ID}^{(2)}$)

What is the Secondary Synchronization Signal (SSS) used for?

Helps UEs achieve frame synchronization and provides the cell identity group ($N_{ID}^{(1)}$)

What components form a Synchronization Signal Block (SSB)?

PSS, SSS, and PBCH (Physical Broadcast Channel)

What is the default periodicity of a 5G SSB?

$$20\,ms$$