In GSM networks enhanced with GPRS, what is the approximate theoretical gross data rate that GPRS can provide when all time slots are used by a single user?

Introduction / Context:
GPRS was introduced to provide higher data rates than basic GSM circuit switched data. The actual throughput depends on coding schemes, radio conditions and how many time slots are assigned to a user. Exam questions often focus on the theoretical gross data rate to test whether you are familiar with benchmark figures used to compare technologies. This question asks for the approximate maximum rate under ideal conditions when all time slots are allocated to one user.

Given Data / Assumptions:

• We are considering an ideal case where a single user can use all eight time slots in a GSM frame for GPRS.
• No error correction overhead, signalling or contention losses are subtracted.
• The question asks for gross, theoretical data rate, not typical real world speeds.

Concept / Approach:
In GPRS, each time slot can carry a certain number of bits per second depending on the coding scheme used. Under favourable conditions with higher order coding, the per slot rate can be about 21.4 kbps. With eight time slots, the theoretical gross rate becomes roughly 8 * 21.4, which is about 171.2 kbps. This value is commonly quoted in textbooks as the peak GPRS data rate. Practical rates are lower due to sharing, error correction and network limitations, but the theoretical benchmark remains around 171 kbps.

Step-by-Step Solution:
Step 1: Recall that GPRS can use multiple time slots per user, up to eight in the ideal case.Step 2: Remember that the highest coding scheme gives approximately 21.4 kbps per time slot.Step 3: Multiply 21.4 kbps by eight time slots to obtain about 171.2 kbps.Step 4: Option C explicitly states approximately 171.2 kbps with all eight slots used.Step 5: Options A, B and D give values that correspond either to far lower rates typical of earlier technologies or to much higher rates associated with later generations, so option C is correct.

Verification / Alternative check:
Most telecommunications textbooks list GPRS peak rates in the range of 171 kbps. They may also present real world user throughput of about 40 to 60 kbps, which is significantly lower. These references consistently distinguish between theoretical gross rate and practical rates, reinforcing that 171.2 kbps is the figure being tested in standard exam questions.

Why Other Options Are Wrong:
Option A, 9.6 kbps, is the typical data rate of original GSM circuit switched data per time slot, not of full slot GPRS. Option B, 56 kbps, is reminiscent of dial up modem speeds and does not match the eight slot GPRS calculation. Option D, around 2 Mbps, corresponds more to later technologies such as early 3G rather than GPRS.

Common Pitfalls:
Candidates sometimes confuse theoretical maximums with practical user experience and may pick a lower value that sounds more realistic. Others memorise figures for EDGE or 3G and mistakenly apply them to GPRS. For exam purposes, make sure to recall that the headline figure for GPRS under optimal conditions is roughly 171.2 kbps, even though real networks rarely reach this speed for a single user.

Final Answer:
Approximately 171.2 kbps when using all eight time slots under ideal conditions.