---
title: "Advantages and disadvantages of CDMA"
subject: "Data Communication"
chapter: 6
key: "semester_5/data_communication:cdma-adv-disadv"
source: https://www.bctengineer.com/q/semester_5/data_communication/cdma-adv-disadv
site: BCT Engineering
---

# Advantages and disadvantages of CDMA

Data Communication · Chapter 6: Multiplexing and Spreading

- Asked in: 2071 Chaitra, 2 marks; 2068 Chaitra, 2 marks (asked 2 times)
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/cdma-adv-disadv
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-6

## Question

What are the advantages and disadvantages of CDMA?

## Short answer

Advantages include efficient spectrum use, resistance to interference and fading, security, soft handoff, and no strict frequency planning. Disadvantages are the near-far problem requiring precise power control, multiple-access interference from imperfectly orthogonal codes, and complex costly equipment.

## Answer

#### Advantages
- All users share the same frequency band at the same time, so spectrum use is efficient and capacity is high.
- Resistant to interference, jamming and multipath fading (RAKE receiver).
- Good security and privacy, since signals look like noise without the code.
- Soft handoff is possible, so fewer dropped calls.
- No strict frequency planning or time synchronisation of slots needed; graceful degradation when more users join.
- Lower power transmission is needed.

#### Disadvantages
- **Near-far problem**: a nearby strong transmitter swamps weak distant ones, so accurate power control is needed.
- Codes are only approximately orthogonal in practice, which causes multiple-access interference when users increase (self-interference limits capacity).
- Complex transmitters and receivers (code generation, synchronisation and power control), so costly.
- Needs wide bandwidth.
- Capacity is "soft" and falls as the noise level rises.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is a CDMA advantage?
   A. Soft handoff
   B. Needs strict slot sync
   C. Narrow bandwidth
   D. Simple receivers
   Answer: A. Soft handoff reduces dropped calls. (Key point: Advantage)

2. What is the near-far problem?
   A. Strong nearby transmitter swamps weak distant ones
   B. Far users have more power
   C. Codes are too orthogonal
   D. Frequency overlap
   Answer: A. Power control is needed. (Key point: Near-far)

3. Why does capacity fall as users increase?
   A. Codes are only approximately orthogonal, causing multiple-access interference
   B. Bandwidth shrinks
   C. Slots run out
   D. Frequencies run out
   Answer: A. Self-interference limits capacity. (Key point: Disadvantage)