Wired and Wireless Connections

Data and information can be encoded in electromagnetic signals and exchanged either physically (wired) or through space (wirelessly). Modern electronic devices can then decode those signals and communicate with other such devices. 1

Wired Connections

When using wired connections, electromagnetic waves travel along physical conductors (typically copper) to carry data from one end to another. In this section we will discuss the transfer of data, but this principle can also be used to carry electric power in the form of a steady current (either AC or DC). Some cables are designed to only carry either data (like standard Ethernet) or power (like DC adapters), while others (like USB) can carry both.

Twisted Pair Cable

Twisted pair cables, such as Ethernet (CAT#, e.g., CAT5 or CAT6, CAT7, CAT8), are the most common wired connections for networks. They carry data using pairs of copper wires and are used in most home and office setups.

Figure 1a: Twisted Pair Cable

These copper wires are crimped into a plastic RJ-45 connector.

Figure 1b: RJ-45 Connector

Coaxial Cable

Coaxial cable has a central copper conductor surrounded by insulation and a braided metal shield, which helps block interference from, for example, fluorescent lights, motors, or other computers. It’s often used for long, one-way data connections like cable TV or broadband internet. Coaxial cable provides good insulation and durability.

Figure 2: Coaxial Cable

Coaxial cable is less susceptible to interference than twisted pair cable.

Fiber Optic Connections

Fiber optic cables are made of thin strands of glass or plastic that carry data as pulses of light. Plastic/glass is not susceptible to electronic interference like traditional copper wired connections. They’re faster and work over longer distances.

Figure 3: Fiber Optic Cable

There are thousands of miles of fiber optic cables laid on the ocean floor that are used to transmit data between different continents. Every 90 miles or so there are repeaters put in place to ensure the data reaches its target uncorrupted2.

A map of undersea fiber optic cables. [Photo: TeleGeography/CC BY-SA]

FeatureTwisted-Pair CableCoaxial CableFiber Optic Cable
StructureTwo insulated copper wires twisted togetherCentral conductor, insulating layer, metallic shield, outer insulating layerCore of glass or plastic fibers, cladding, protective outer layer
BandwidthUp to 1 Gbps for Cat 5e, higher for Cat 6, Cat 7Up to 10 Mbps (traditional), higher for modern cables10 Gbps to 100 Gbps and beyond
DistanceUp to 100 metersUp to 500 meters for broadband, 185 meters for basebandUp to 40 km for single-mode, 2 km for multi-mode
InterferenceSusceptible to electromagnetic interferenceBetter resistance to interference than twisted-pairImmune to electromagnetic interference
CostLowModerateHigh
SecurityModerate (can be tapped with physical access)Higher security due to shieldingVery secure (difficult to tap)
ApplicationsLocal Area Networks (LANs), telephone networksCable TV, internet, and telecommunicationsBackbone networks, long-distance communication
Summary of the Wired Media Connections

Wireless Connections

802.11 Wireless Standards

Wi-Fi is a form of wireless communication that uses radio waves to broadcast a signal. It’s based on the Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless standards, which define how computers connect to networks without wires.

There are several specifications in the 802.11 family:

StandardFrequency (Ghz)Max Speed (Mbps)Range (ft)
802.11a554115
802.11b2.411100
802.11g2.454140
802.11n5450230
802.11ac51300230
802.11ax5 – 69608variable

For a more detailed table about the 802.11 wireless standard variations, see: https://en.wikipedia.org/wiki/Wi-Fi

Wi-Fi symbol
Wi-Fi symbol

Other Wireless Methods:

Bluetooth is a set of protocols / standards for communicating wirelessly on 2.4 GHz frequency (like WiFi) at short ranges. Its uses include headphones, game controller, stylus, keyboard / mouse, speakers, mobile phones, where you can pair different devices together3. Most Bluetooth devices have a range of 10m, but the technology does allow for ranges up to 100m.

Bluetooth symbol
Bluetooth symbol

Cell Phone Internet

Cell Phones provide services like phone calls, text messaging, multimedia messaging, email, internet access (via LTE, 5G NR or Wi-Fi), and short-range wireless technologies like Bluetooth, infrared, and ultra-wideband (UWB). The main standard for cell phone network connections is the G standard, going from 1G to 5G (at the time of writing), although 6G is planned for the future. 5G has faster downloads, lower latency, and support for more connected devices than 4G or 3G. Downloads have a peak speed of 10 gigabits per second in 5G. (Gbit/s) or Gb is gigabit, note the use of the lowercase b for bit rather than B for byte.

Exercises

Some networking math. A byte is 8 bits. You may want to read the binary chapter first to help you with these.

  • Example: 1500 byte packet, 1500 * 8 = 12000 bits
  1. How many megabytes per second can a 100 mbps network send ignoring overhead?
  2. How many seconds are required to send 1500 byte packet on 100 megabit network?
  3. I have a 38 MB image. How long to send at 100 mbps?
  1. Explore: What’s the difference between the various CAT# that are available? CAT4, CAT5, CAT6, etc.?
  2. You likely use 4G or 5G daily on your phone, and you might be familiar with Samuel Morse and the telegraph. How were people able to take the telegraph and turn it into what we can do nowadays? How might it look in the future?

References

  1. How Wi-Fi Works: From Electricity to Information ↩︎
  2. See Fast Company, Nearly all data that moves around the world goes through these undersea cables ↩︎
  3. Reference: Rob Parke, ITP 348. ↩︎