In a basic GSM system without packet data enhancements, what is the typical maximum data rate supported per user on a single time slot?

Introduction / Context:
Before the introduction of packet data services such as GPRS and EDGE, GSM networks offered limited circuit switched data services. Understanding the baseline data capability of pure GSM is important when studying the evolution of mobile communications. This question focuses on the typical maximum data rate per user in a basic GSM system using one time slot for circuit switched data.

Given Data / Assumptions:

• We are considering original GSM circuit switched data without enhancements like GPRS or EDGE.
• Each user is allocated a single time slot for data communication.
• The question asks for a typical maximum data rate, not an absolute theoretical limit with multiple slots or special coding.

Concept / Approach:
GSM was optimised for digital voice, and its early data services were relatively slow. Standard circuit switched data connections over GSM provided around 9.6 kbps per time slot. Some improvements allowed 14.4 kbps per slot in later implementations, but the commonly quoted figure in introductory material is 9.6 kbps. This value is much lower than what became possible with GPRS and later generations, highlighting why packet based upgrades were necessary for practical mobile internet.

Step-by-Step Solution:
Step 1: Recall that original GSM circuit switched data targeted a speed of about 9.6 kbps per channel.Step 2: Recognise that this rate is associated with a single time slot allocated for data.Step 3: Option A gives approximately 9.6 kbps per time slot, matching the standard teaching value.Step 4: Option B, 64 kbps, corresponds to an ISDN B channel but not to basic GSM per user on one slot.Step 5: Options C and D list much higher data rates characteristic of 3G or GPRS enhancements, not basic GSM, so option A is correct.

Verification / Alternative check:
Historical GSM specifications and training materials often cite 9.6 kbps as the data speed available for circuit switched connections. While some operators later deployed configurations that allowed 14.4 kbps per slot or used multiple slots, the baseline figure remains 9.6 kbps. This number is widely used when comparing pure GSM data capabilities to later technologies, confirming that option A reflects the expected answer.

Why Other Options Are Wrong:
Option B exaggerates the per user data rate by equating it with ISDN B channel speeds, which are not directly applicable to basic GSM slots. Option C and option D give values in the hundreds of kilobits or megabits per second, which belong to advanced technologies such as GPRS, EDGE or 3G networks rather than original GSM.

Common Pitfalls:
Candidates may confuse the many different data rates associated with GSM and its extensions. A common mistake is to remember only the improved speeds from later upgrades and then apply those values to pure GSM. To avoid confusion, it helps to remember one simple fact: early GSM data was roughly in the 9.6 kbps range, which is why enhanced technologies were needed for realistic internet usage.

Final Answer:
Approximately 9.6 kbps per time slot for circuit switched data.