---
title: "Forward and reverse channel"
subject: "Wireless Communication"
chapter: 1
key: "semester_7/wireless_communication:forward-reverse-channel"
source: https://www.bctengineer.com/q/semester_7/wireless_communication/forward-reverse-channel
site: BCT Engineering
---

# Forward and reverse channel

Wireless Communication · Chapter 1: Introduction

- Asked in: 2080 Bhadra, 2 marks
- Video: [Uplink and Downlink communication – Forward and Reverse Channels](https://www.youtube.com/watch?v=r7196pdGpew) — Commsbrief Limited Official
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/wireless_communication/forward-reverse-channel
- Whole chapter: https://www.bctengineer.com/md/semester_7/wireless_communication/chapter-1

## Question

Define forward and reverse channel.

## Short answer

The forward channel (downlink) transmits from base station to mobile; the reverse channel (uplink) transmits from mobile to base station. Both carry traffic and control information.

## Answer

- **Forward channel (downlink):** the radio channel used to carry information **from the base station to the mobile user**. Example: in GSM-900 the forward band is 935–960 MHz.
- **Reverse channel (uplink):** the radio channel used to carry information **from the mobile user to the base station**. Example: in GSM-900 the reverse band is 890–915 MHz.

Both directions contain voice (traffic) channels and control channels. The control channels (forward control channel and reverse control channel) carry call set-up, paging and access messages.

## Check yourself

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

1. Which direction does the forward channel carry information?
   A. Base station to mobile user
   B. Mobile user to base station
   C. Between two base stations
   D. Between two mobiles directly
   Answer: A. Forward = downlink. (Key point: Forward channel)

2. Which is a reverse channel example?
   A. GSM-900 935-960 MHz
   B. GSM-900 890-915 MHz
   C. Paging only
   D. Any control channel
   Answer: B. Reverse (uplink) band of GSM-900 is 890-915 MHz. (Key point: Reverse channel)

3. What are control channels used for?
   A. Carrying the voice conversation
   B. Call set-up, paging and access
   C. Duplexing
   D. Power amplification
   Answer: B. Traffic channels carry voice; control channels handle set-up, paging and access. (Key point: Control channels)

## Related in Wireless Communication

- [Forward/reverse channel and 5G versus 4G](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Aforward-reverse-5g-vs-4g) — Wireless Communication, chapter 1, asked 2×
- [Forward/reverse channel and features of 5G](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Aforward-reverse-5g-features) — Wireless Communication, chapter 1
- [Forward CDMA (IS-95) channel](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Aforward-cdma-is95-channel) — Wireless Communication, chapter 8, asked 4×
- [Reverse CDMA (IS-95) channel](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Areverse-cdma-is95-channel) — Wireless Communication, chapter 8

## Related in other subjects

- [Forward vs reverse engineering merits and demerits](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Aforward-reverse-engineering-merits) — Object Oriented Analysis and Design, chapter 4, asked 3×
- [Short note: Information in forward/reverse engineering](https://www.bctengineer.com/question.md?key=semester_6%2Fobject_oriented_analysis_and_design%3Ashort-note-information-content-forward-reverse) — Object Oriented Analysis and Design, chapter 4
- [Forward and reverse biased pn junction](https://www.bctengineer.com/question.md?key=semester_3%2Felectrical_engineering_material%3Aforward-reverse-bias) — Electrical Engineering Material, chapter 6