Chapter 7: Wireless and SOHO Networks

A+ Core 1 — 220-1101 | Domains 2.3, 2.5, 2.7

Chapter 7:
Wireless & SOHO Networks

IEEE 802.11 standards, Bluetooth, cellular, internet connection types, wireless security, and SOHO network configuration. These topics appear across multiple A+ Core 1 objectives.

21 Slides Domains 2.3, 2.5, 2.7 Wi-Fi • Security • Cellular • SOHO Exam 220-1101

Slide 2 of 21

IEEE 802.11 Fundamentals

CSMA/CA governs how wireless devices share a radio channel without collisions.

CSMA/CA — How It Works

1. Listen: Check if channel is clear.
2. Wait: If busy, back off a random time.
3. RTS: Send Request to Send to AP.
4. CTS: AP replies Clear to Send.
5. Transmit: Send data frame.
6. ACK: Receiver confirms receipt.

2.4 GHz Band

Pros: Better range, penetrates walls well.
Cons: Crowded band (microwaves, Bluetooth, neighboring Wi-Fi), fewer non-overlapping channels.
Non-overlapping: 1, 6, 11 (US). Must be 5 channels apart to avoid overlap.

5 GHz Band

Pros: Less congestion, many more channels, faster throughput.
Cons: Shorter range, blocked by walls and floors.
DFS Channels: Shared with weather radar — AP may auto-switch if radar detected.

CSMA/CA vs CSMA/CD

Wired Ethernet uses CSMA/CD (Collision Detection) because it can detect collisions in real time. Wireless cannot — a transmitting device cannot simultaneously listen, so it uses Collision Avoidance via the RTS/CTS handshake instead.

Slide 3 of 21

Wireless Modulation Techniques

How data is encoded onto a radio signal has evolved with each 802.11 generation.

Technique	Abbreviation	Description	Used By
Frequency-Hopping Spread Spectrum	FHSS	Rapidly hops between frequencies	Original 802.11, Bluetooth
Direct-Sequence Spread Spectrum	DSSS	Spreads signal across wider band	802.11b
Orthogonal Frequency Division Multiplexing	OFDM	Splits data across multiple subcarriers	802.11a/g/n/ac
OFDM Multiple Access	OFDMA	OFDM with simultaneous multi-user support	802.11ax (Wi-Fi 6)

Why OFDM Dominates

OFDM splits one channel into many sub-channels (subcarriers), each carrying a portion of the data. This makes it resistant to interference and multipath reflections — the primary reason 802.11a/g/n/ac all use it.

OFDMA (Wi-Fi 6 Upgrade)

OFDMA extends OFDM by letting the AP serve multiple clients simultaneously on different subcarriers within the same channel. Key efficiency gain in high-density environments like classrooms and stadiums.

Slide 4 of 21

Wi-Fi Standards: 802.11 a/b/g/n/ac/ax

Every revision of 802.11 brought higher speeds, new frequencies, or better multi-user efficiency.

Standard	Wi-Fi Name	Frequency	Max Speed	Modulation	Indoor Range
802.11 (legacy)	—	2.4 GHz	2 Mbps	FHSS / DSSS	20 m
802.11a	—	5 GHz	54 Mbps	OFDM	35 m
802.11b	—	2.4 GHz	11 Mbps	DSSS	40 m
802.11g	—	2.4 GHz	54 Mbps	DSSS / OFDM	40 m
802.11n	Wi-Fi 4	2.4 / 5 GHz	600 Mbps	OFDM / DSSS	70 m
802.11ac	Wi-Fi 5	5 GHz only	6.9 Gbps	OFDM	35 m
802.11ax	Wi-Fi 6	2.4 / 5 GHz	9.6 Gbps	OFDMA	35 m

Exam Tip: 802.11ac = 5 GHz Only

Wi-Fi 5 (802.11ac) operates exclusively on 5 GHz. If an exam question pairs 802.11ac with 2.4 GHz, the answer is wrong. This is one of the most-tested traps on the A+ Core 1 exam.

Memory Aid

Order of standards by release: a, b, g, n, ac, ax.
"All Boys Get New AC Axes" locks the sequence.

Slide 5 of 21

Key Standards: n, ac, ax

The three modern standards that appear most frequently on the A+ exam.

802.11n — Wi-Fi 4

First dual-band standard (2.4 + 5 GHz). Introduced MIMO (Multiple-Input Multiple-Output) with up to 4 spatial streams. Channel bonding allows 40 MHz wide channels, doubling throughput versus single 20 MHz channels.

802.11ac — Wi-Fi 5

5 GHz only. Introduced MU-MIMO (Multi-User MIMO) — AP can transmit to multiple clients simultaneously on downlink. Up to 8 spatial streams. Supports 80 MHz and 160 MHz wide channels. Theoretical max 6.9 Gbps.

802.11ax — Wi-Fi 6

Designed for high-density environments. OFDMA serves multiple clients per transmission. Target Wake Time (TWT) extends IoT device battery life. BSS Coloring reduces interference between overlapping networks. Wi-Fi 6E adds 6 GHz band (US, 2020).

WAP vs. Wireless Router

A Wireless Access Point (WAP) is a Layer 2 device connecting wireless clients to a wired network. It does not route. A Wireless Router combines router + switch + WAP. Provides NAT, DHCP, and firewall. Standard in SOHO environments.

6 GHz Band (Wi-Fi 6E)

Released 2020 in the US. No legacy devices on this band = zero congestion from older gear. Requires new hardware on both AP and client side. Best for high-density, high-throughput deployments where latency matters.

Slide 6 of 21

Bluetooth Networking

Short-range, low-power communication in the 2.4 GHz ISM band using FHSS.

Bluetooth Classes (Range vs. Power)

Class 1: 100 m / 100 mW — industrial USB adapters
Class 2: 10 m / 2.5 mW — headphones, keyboards, mice
Class 3: 1 m / 1 mW — specialty devices
Class 4: 0.5 m / 0.5 mW — ultra-low power sensors

Bluetooth Versions

1.x: Basic Rate only
2.x: + Enhanced Data Rate (EDR)
3.x: + High Speed (HS) — uses Wi-Fi for data
4.x: + Bluetooth Low Energy (BLE)
5.x: + Slot Availability Masking (SAM), 2x speed, 4x range

Exam Tip: BLE

Bluetooth Low Energy (BLE) was introduced in version 4.0. It is used by fitness trackers, IoT sensors, and proximity beacons. BLE maintains the same range as classic Bluetooth Class 2 while consuming approximately 50% less power. Know the version (4.0) for the exam.

A user complains their wireless headphones disconnect when they walk to the kitchen. The headset is Class 2. The phone stays on the desk 12 meters away. Class 2 rated range is 10 meters — the user is out of range. Upgrade to a Class 1 device or keep the phone closer.

Slide 7 of 21

RFID and NFC

Radio-frequency identification for asset tracking; NFC for contactless transactions at very short range.

RFID Type	Frequency	Read Distance	Use Case
Low Frequency (LF)	125–134 kHz	10 cm	Animal tracking, building access cards
High Frequency (HF)	13.56 MHz	30 cm	Smart cards, library books
Ultra-High Frequency (UHF)	856–960 MHz	100 m	Inventory, retail supply chain

NFC Basics

NFC is a subset of HF RFID operating at 13.56 MHz. Range is approximately 4 cm. Designed for tap-to-pay and tap-to-pair interactions. Both passive (tags) and active (devices) modes supported.

NFC: Card Emulation

Device acts as a contactless smart card. Primary use: contactless payments (Apple Pay, Google Pay, Samsung Pay). The reader sees the phone as a payment card.

NFC: Peer-to-Peer

Two NFC-enabled devices exchange data directly. Used by Android Beam and similar file-transfer features. Both devices must be active (powered).

Slide 8 of 21

Internet Connection Types

Understanding medium, speed, and trade-offs for each connection type is required for 2.7.

Connection Type	Speed Range	Medium	Key Characteristics
Dial-up (POTS)	Up to 56 Kbps	Phone line	Legacy, ties up phone line during use
DSL	1–100 Mbps	Phone line	Distance-sensitive, always-on, does not tie up voice
Cable	25 Mbps–1 Gbps	Coaxial (DOCSIS)	Shared neighborhood bandwidth
Fiber	100 Mbps–10 Gbps	Fiber optic	Fastest residential option; highest cost to deploy
Satellite (GEO)	12–100 Mbps	Wireless (35,786 km)	600+ ms latency; weather-affected; no VoIP/gaming
Satellite (LEO)	50–500 Mbps	Wireless (500–2,000 km)	20–40 ms latency; Starlink; line-of-sight required
Cellular	1 Mbps–1+ Gbps	Wireless (cellular)	Mobile, subject to data caps and carrier throttling
WISP	Varies	Fixed wireless	Point-to-point; rural/underserved; antenna at premises

Exam Tip: Satellite Latency

GEO satellites orbit at ~35,786 km. Round-trip signal time equals 600+ ms, making them unsuitable for real-time protocols (VoIP, gaming, video conferencing). LEO constellations are the modern answer to high-latency satellite — know both types.

Slide 9 of 21

DSL Types & Fiber Deployment

Not all DSL is the same; fiber delivery varies based on how far the glass runs.

ADSL — Asymmetric

Download speed exceeds upload speed. Optimized for home consumers who download more than they upload. Up to 24 Mbps downstream. Performance degrades with distance from the telephone exchange.

SDSL — Symmetric

Equal upload and download speeds. Preferred for businesses that host servers or conduct regular large uploads. Typical speeds: 1–7 Mbps. More expensive than ADSL for the same distance.

VDSL — Very High-Speed

Fastest DSL variant — up to 100 Mbps. Requires shorter copper runs; typically requires fiber to the curb or node. Often deployed as part of fiber/copper hybrid infrastructure.

FTTH / FTTP

Fiber to the Home / Premises. Glass fiber runs all the way into the building. Maximum performance. Highest deployment cost.

FTTC

Fiber to the Curb. Fiber reaches the neighborhood distribution point. Short copper run to the actual building. Good performance, lower cost than FTTH.

FTTN

Fiber to the Node. Fiber reaches a local cabinet serving a wider area. Longer copper last mile. Performance limited by copper distance.

Slide 10 of 21

Cellular: 3G / 4G / 5G

Mobile networking generations — each doubled down on speed, capacity, and all-IP architecture.

GSM — Global System for Mobile

Carriers: AT&T, T-Mobile (US)
SIM card: Yes — removable, carrier-locked by subscription
International: Used worldwide; swap SIM abroad
Speed: Up to 7 Mbps (HSPA)

CDMA — Code-Division Multiple Access

Carriers: Verizon, Sprint (legacy)
SIM card: No — device identity is in the network
International: Limited; phone locked to carrier hardware
Speed: Up to 7 Mbps (EV-DO)

Critical Exam Fact

GSM and CDMA are not compatible. A GSM phone cannot connect to a CDMA network and vice versa. The exam will present swap scenarios — if the question involves swapping a SIM card, the answer always involves GSM.

Generation	Speed	Technology	Key Feature
4G / LTE	10–300 Mbps	Long Term Evolution	All-IP architecture; replaces circuit switching
5G Sub-6 GHz	100–900 Mbps	NR (New Radio)	Wide coverage; urban and suburban
5G mmWave	Multi-Gbps	24–100 GHz	Dense urban, stadiums; <300 m range

Slide 11 of 21

5G Band Architecture

Three frequency bands with distinct speed/range trade-offs; plus mobile connectivity options.

Low-Band (Sub-1 GHz)

Excellent geographic coverage; penetrates buildings well. Speed is only a modest improvement over 4G LTE. Primary band for rural 5G rollout and national coverage claims.

Mid-Band (1–6 GHz)

Good balance of range and speed. Typical throughput 100–900 Mbps. Primary band for urban and suburban 5G deployments. Most modern 5G phones operate here.

mmWave (24–100 GHz)

Multi-gigabit throughput. Range limited to approximately 300 meters; blocked by buildings, glass, and foliage. Deployed in dense venues: stadiums, airports, convention centers.

Tethering

Share a phone's mobile data connection with another device via USB cable, Bluetooth, or Wi-Fi hotspot. Requires carrier plan support. Battery impact is significant.

Mobile Hotspot

Phone broadcasts a Wi-Fi access point backed by the cellular data connection. Multiple devices can connect simultaneously. Dedicated hotspot devices eliminate phone battery drain.

5G Latency Goal

Theoretical target: 1 ms. Real-world typical: 5–20 ms. This enables use cases impossible on 4G: autonomous vehicles, remote surgery, real-time industrial control.

Slide 12 of 21

Wired Network Standards

Ethernet naming convention: Speed + Signaling type + Medium. Cable category determines maximum distance.

Standard	Cable Required	Speed	Max Distance
10BaseT	Cat 3+	10 Mbps	100 m
100BaseTX	Cat 5+	100 Mbps	100 m
100BaseFX	Multi-mode fiber	100 Mbps	2,000 m
1000BaseT	Cat 5e+	1 Gbps	100 m
10GBaseT	Cat 6 (55 m) / Cat 6a+ (100 m)	10 Gbps	55–100 m
25GBaseT / 40GBaseT	Cat 8	25–40 Gbps	30 m
10GBaseSR	Multi-mode fiber	10 Gbps	300 m
10GBaseLR	Single-mode fiber	10 Gbps	10 km

Exam Trap: 10GBaseT with Cat 6

Cat 6 supports 10 GBaseT only to 55 meters. At longer runs you need Cat 6a or better to reach the full 100 m. Questions describe why 10 Gbps fails at 80 m — the answer is Cat 6 cable distance limit, not equipment failure.

Slide 13 of 21

Twisted Pair vs. Fiber

Choosing the right medium comes down to distance, EMI environment, speed, and budget.

Characteristic	Twisted Pair (UTP/STP)	Fiber Optic
Max Speed	Up to 40 Gbps (Cat 8)	100+ Gbps
Max Distance	100 m standard	40+ km (single-mode)
EMI Susceptibility	Yes — vulnerable to interference	No — immune to EMI
Installation	Easy — standard crimp tools	Requires fusion splicing or polishing
Connector	RJ-45	SC, ST, LC
Cost	Inexpensive	Expensive (cable + transceivers)

When to Use Fiber

Runs exceeding 100 m. High-EMI environments (factory floors, power rooms, elevator shafts). Inter-building connections. Any run requiring more than 10 Gbps over copper distances.

Fiber Connector Types

SC (Subscriber Connector): Square push/pull, snap-in.
ST (Straight Tip): Round bayonet, twist-lock.
LC (Lucent Connector): Small form-factor, push/pull latch. Most common in modern data centers.

Multi-mode vs. Single-mode

Multi-mode: Larger core, LED source, shorter runs (up to ~550 m at 10 Gbps). Orange or aqua cable.
Single-mode: Narrow core, laser source, long haul (km range). Yellow cable.

Slide 14 of 21

SOHO Network Planning

Small Office / Home Office deployments follow a consistent planning sequence before any cable is pulled.

Planning Sequence

1. Understand local regulations and wireless restrictions.
2. Obtain floor plan or site map.
3. Locate server(s) in a central, secure spot.
4. Identify client workstation locations.
5. Locate shared resources (printers, NAS).
6. Determine wired vs. wireless for each area.
7. Designate connectivity zones (conference rooms, lobbies).

AP Placement Rules

Coverage overlap: 10–20% between neighboring APs to enable seamless roaming without dead zones.
Same SSID: All APs in a roaming zone share one network name.
Non-overlapping channels: Adjacent APs use channels 1, 6, 11 on 2.4 GHz to prevent co-channel interference.

Channel Rule: 1-6-11

In the 2.4 GHz band each channel is 5 MHz wide but occupies 20 MHz of spectrum. Channels must be at least 5 numbers apart to avoid overlap. 1, 6, 11 are the only three non-overlapping channels available in the US. This is one of the most-tested facts on the A+ exam across multiple domains.

A SOHO deployment has two APs both set to channel 6 in adjacent offices. Users report slow Wi-Fi and frequent drops. Root cause: co-channel interference. Fix: set one AP to channel 1 and the other to channel 11. Immediately resolved.

Slide 15 of 21

Wireless Security: WEP to WPA3

Encryption protocols evolved as each predecessor was broken. Know the cipher, the flaw, and the status of each.

Protocol	Year	Encryption	Key Size	Status
WEP	1997	RC4	64 / 128-bit	BROKEN — Never Use
WPA	2003	TKIP (RC4)	128-bit	Deprecated 2012
WPA2	2004	CCMP (AES)	128-bit	Acceptable
WPA3	2018	GCMP (AES)	128 / 192-bit	Recommended

WEP Flaw

WEP uses a 24-bit Initialization Vector (IV). With only 16 million possible IVs, the IV repeats on a busy network within minutes. Reused IVs allow attackers to recover the full encryption key. Freely available tools crack WEP in under 60 seconds. If you see WEP on a live network, escalate immediately.

Exam Tip: Cipher Pairings

WEP and WPA both use RC4. WPA2 and WPA3 use AES. TKIP was a temporary RC4 patch for WPA. CCMP is the proper AES-based implementation in WPA2+. Know the cipher for each protocol — this appears frequently in scenario questions.

Slide 16 of 21

WPA3 Features & Auth Modes

WPA3 closes every known attack vector against WPA2 and adds forward secrecy.

WPA3 Improvements

SAE (Simultaneous Authentication of Equals): Replaces PSK handshake; resistant to offline dictionary attacks.
Forward Secrecy: Past traffic cannot be decrypted even if the passphrase is later compromised.
Easy Connect: QR-code-based provisioning for IoT devices.
Enhanced Open: Opportunistic encryption on open public networks.

WPA2 Personal vs. Enterprise

Personal (PSK): Single shared passphrase for all clients. Simple setup for homes and small offices. If the passphrase leaks, all clients are exposed.
Enterprise (802.1X / EAP): Each user authenticates with unique credentials against a RADIUS server. Scales to thousands of users. Compromised credentials affect one account only.

Mode	Auth Method	Use Case	Scalability
Personal (PSK)	Shared passphrase	Home, small office	Limited
Enterprise (802.1X)	RADIUS + EAP	Corporate, education	Excellent
WPA3-SAE	Dragonfly handshake	Modern SOHO	Good
WPA3-Enterprise	RADIUS + 192-bit AES	High-security environments	Excellent

Slide 17 of 21

Wireless Router Configuration

Five mandatory steps and the security features every A+ technician must know how to configure.

5 Mandatory Config Steps

1. Change SSID from factory default.
2. Change admin username and password (strong, unique).
3. Select WPA2 or WPA3 with AES encryption.
4. Set a strong passphrase (12+ characters).
5. Connect clients using matching security settings.

Router Security Services

Firewall: Enable — default on most routers.
NAT: Enable — required for private addressing.
DMZ: Use sparingly; exposes host to full internet.
UPnP: Disable — exploited by malware to open ports.
MAC Filtering: Weak; MACs are spoofable — supplemental only.
Guest Network: Isolates guest traffic from primary LAN.

Disable UPnP

Universal Plug and Play allows devices to automatically request port forwarding rules. While convenient, malware on the network can use UPnP to open inbound ports without user awareness. On the A+ exam, UPnP is always listed as a security risk to disable.

SSID Hiding is Not Security

Disabling SSID broadcast provides no real protection. Network scanners and passive sniffers reveal hidden SSIDs instantly. It adds inconvenience for legitimate users while providing minimal deterrence. Strong WPA2/WPA3 + passphrase is the actual defense.

Slide 18 of 21

Firewall, NAT, and Port Forwarding

Layer-by-layer network protection in a SOHO environment.

Network-Based Firewall

Hardware device or router-integrated feature. Filters traffic at the network perimeter before it reaches any host. Applies rule sets to inbound and outbound traffic based on IP, port, and protocol. Protects the entire network from a single control point.

Host-Based Firewall

Software installed on an individual device. Examples: Windows Defender Firewall, iptables on Linux. Filters traffic at the endpoint. Provides protection even when the host is on an untrusted network such as a hotel or coffee shop Wi-Fi.

NAT — Network Address Translation

Translates private (RFC 1918) IP addresses to a single public IP address. Allows many devices to share one public IP. Provides incidental security by hiding internal addressing. Port Address Translation (PAT) is the specific form used in SOHO routers.

Port Forwarding

Routes inbound traffic on a specific external port to a designated internal host and port. Required to host a web server, game server, or remote desktop behind NAT. Example: external port 80 → internal 192.168.1.10:80.

DMZ (Demilitarized Zone)

Exposes a single internal host to all inbound internet traffic (all ports). Used for servers that need full external accessibility. The DMZ host is still protected by host-based firewall. Never place a personal workstation in the DMZ.

Slide 19 of 21

Exam Practice: Quick Questions

Six A+ style scenario questions — answers in gold. Cover them first.

Q1

A technician deploys three APs in a long office building on 2.4 GHz. All are set to channel 6. Users in the middle report poor performance. What is the root cause and fix? — Co-channel interference. Set the three APs to channels 1, 6, and 11 respectively.

Q2

A customer's wireless router still shows WEP as the security protocol after an office move. What action is required? — Immediately upgrade to WPA2 or WPA3. WEP is completely broken and can be cracked in seconds.

Q3

A 10 Gbps Ethernet run of 80 meters is not achieving full speed. Cat 6 cable was used. What is the problem? — Cat 6 supports 10GBaseT only to 55 m. Cat 6a or better is needed for 100 m at 10 Gbps.

Q4

A user needs to swap their phone to a different carrier while traveling internationally. Which cellular standard makes this possible? — GSM. It uses a removable SIM card. CDMA phones are locked to carrier hardware without a SIM.

Q5

A satellite Internet customer complains that VoIP calls are constantly breaking up despite 50 Mbps download speed. What is the issue? — GEO satellite latency (600+ ms). VoIP requires <150 ms for acceptable quality. Upgrade to LEO (Starlink) or a terrestrial connection.

Q6

A SOHO router admin wants to prevent IoT devices from automatically opening ports. Which feature must be disabled? — UPnP (Universal Plug and Play). It allows devices to self-configure port forwarding rules — a known malware attack vector.

Slide 20 of 21

Key Vocabulary

Chapter 7 terms organized by category.

802.11 Standards

CSMA/CA — collision avoidance via RTS/CTS
OFDM / OFDMA — modulation; OFDMA = multi-user
MIMO / MU-MIMO — spatial streaming; MU = multi-user
802.11ac — Wi-Fi 5; 5 GHz only
802.11ax — Wi-Fi 6; OFDMA; TWT; BSS coloring
Channels 1, 6, 11 — non-overlapping 2.4 GHz

Short-Range Wireless

Bluetooth Class 1/2/3 — 100 m / 10 m / 1 m range
BLE — Bluetooth Low Energy; introduced v4.0
FHSS — frequency hopping; used by Bluetooth
RFID LF/HF/UHF — 10 cm / 30 cm / 100 m
NFC — 13.56 MHz; ~4 cm range; HF RFID subset
SAE — WPA3 handshake; replaces PSK

Internet & Security

ADSL / SDSL / VDSL — DSL variants by symmetry
FTTH / FTTC / FTTN — fiber delivery tiers
GEO / LEO — satellite orbit; latency trade-off
GSM / CDMA — cellular; SIM vs. no SIM
WPA2 CCMP / WPA3 GCMP — AES-based encryption
NAT / UPnP / DMZ — router features; UPnP disable

Slide 21 of 21 — Chapter 7 Complete

Chapter 7 Summary

Eight key takeaways from Wireless and SOHO Networks.

1

Non-overlapping 2.4 GHz channels are 1, 6, 11. Adjacent APs must use different channels from this set to avoid co-channel interference.

2

802.11ac (Wi-Fi 5) is 5 GHz only. It does not operate on 2.4 GHz. Any exam question pairing ac with 2.4 GHz is incorrect.

3

WEP is broken. RC4 with a 24-bit IV is crackable in seconds. WPA2 uses CCMP/AES. WPA3 adds SAE (Dragonfly) and forward secrecy.

4

GSM uses SIM cards; CDMA does not. Swapping phones or carriers internationally requires GSM. CDMA phones are locked to carrier hardware.

5

GEO satellite latency exceeds 600 ms — unsuitable for VoIP or gaming. LEO (Starlink) drops this to 20–40 ms. Know both for troubleshooting questions.

6

Cat 6 limits 10GBaseT to 55 meters. Cat 6a, Cat 7, or Cat 8 required for 100 m runs at 10 Gbps. This is a frequent cable-troubleshooting scenario.

7

Disable UPnP on SOHO routers. It allows devices to auto-configure port forwarding, which malware exploits to open inbound ports without user knowledge.

8

BLE was introduced in Bluetooth 4.0. It runs in 2.4 GHz using FHSS, consumes ~50% less power than classic Bluetooth, and is used by IoT devices, fitness trackers, and beacons.