GSM/GPRS/EGPRS Throughput Explained

Throughput is a key performance indicator for both wired and wireless communication systems. In the context of GSM/GPRS/EGPRS, it essentially measures the rate at which data can be successfully transmitted through the network.

It’s usually specified in bits per second (bps) per time slot and is often referred to as the data rate. Since GPRS is commonly used for internet access on GSM networks, we’ll focus on throughput related to GPRS coding schemes.

The following table outlines the theoretical maximum throughput achievable in a GPRS network for different coding schemes (CS1, CS2, CS3, and CS4) when data is allocated to a single time slot. The lower end of the range applies when there are approximately 100 active users, while the upper end applies when there is only 1 active user in the cell. If multiple time slots are used, simply multiply the values by the number of slots to get the total throughput. Throughput will also differ between acknowledged and unacknowledged transmission modes in GPRS.

GPRS Throughput Table

Normalized Throughput

Normalized throughput can be calculated as:

Normalized throughput = Total data received correctly / Total Data Transmitted

Typically, the normalized throughput is higher in unacknowledged transmission mode compared to acknowledged mode. This is because, in unacknowledged mode, any incorrect frames are discarded. In acknowledged mode, however, incorrect frames are re-transmitted, leading to an increase in the total data transmitted and, therefore, a decrease in normalized throughput.

To improve throughput in acknowledged transmission mode, it’s crucial to minimize retransmissions as much as possible.

EGPRS/EDGE Throughput

The following table shows the throughput for EGPRS/EDGE modulation coding schemes: MCS1, MCS2, MCS3, MCS4, MCS5, MCS6, MCS7, MCS8, and MCS9.

EGPRS/EDGE Max. Throughput Table