In local area networking, which transmission medium is traditionally associated with broadband LANs that use frequency-division techniques and multiple channels?

Introduction:
LANs historically used two contrasting physical-layer styles: baseband, sending one digital signal over the medium at a time, and broadband, partitioning spectrum into multiple channels using frequency-division techniques. Knowing which media align with each style clarifies legacy Ethernet variants and campus cabling choices.

Given Data / Assumptions:

• “Broadband local networks” refers to LANs using multiple RF-like channels over the same medium.
• We compare common LAN media: coaxial cable, optical fiber, UTP (twisted pair), and CATV (a system rather than a bare medium).
• We seek the traditional association in networking curricula.

Concept / Approach:
Broadband LANs (e.g., early IEEE 802.7 and 10Broad36) used coaxial cable because its shielding and frequency response support multiple modulated channels on one physical plant—much like community antenna television (CATV) systems. By contrast, classic Ethernet over UTP (10BASE-T/100BASE-TX) is baseband; fiber in LANs is also typically used for baseband digital signaling (though fiber can carry many wavelengths, “broadband LAN” historically maps to coaxial implementations).

Step-by-Step Solution:
Identify broadband = FDM, multiple simultaneous channels.Match to coaxial cable’s widespread use in broadband/CATV and 10Broad36.Recognize UTP and typical LAN fiber as baseband in standard Ethernet deployments.Select “Coaxial cable.”

Verification / Alternative check:
Standards histories show 10Broad36 (broadband Ethernet over 75-ohm coax) alongside baseband 10BASE5/10BASE2, confirming coax’s role.

Why Other Options Are Wrong:

• optic fiber: commonly baseband in LAN Ethernets; broadband in telecom WDM context, but not the historic “broadband LAN” answer.
• CATV: a system that often uses coax; the question asks for a medium.
• UTP: baseband Ethernet medium.
• None of the above: invalid because coaxial cable is correct.

Common Pitfalls:
Confusing broadband vs. baseband, or mixing the CATV system concept with the underlying medium choice.

Final Answer:
Coaxial cable