GSM vs. GSM Advanced: A Comparative Overview

This document outlines the key differences between GSM (Global System for Mobile Communications) and GSM Advanced, charting the progress from the first cellular system to its more sophisticated successor. We also provide links to resources explaining various related concepts.

GSM is widely recognized as the world’s first cellular system and currently boasts over a billion subscribers globally. It operates across multiple frequency bands depending on the region and application. Popular bands include GSM-850, GSM-900, DCS-1800, and PCS-1900. Each unique RF frequency is assigned a specific ARFCN (Absolute Radio Frequency Channel Number). You can learn more by referring to a GSM ARFCN vs. Frequency table and calculator.

Core GSM Architecture

In GSM, the two fundamental components are the Base Station (BS) and Mobile Station (MS). The communication link from the BS to the MS is known as the downlink, while the link from the MS to the BS is the uplink. Resource allocation relies on FTDMA (Frequency-Division Multiple Access and Time-Division Multiple Access). Therefore, two-way communication between the BS and MS requires a frequency and time slot pair. For a more in-depth explanation, refer to a GSM tutorial.

Advancements in GSM Advanced

GSM Advanced introduces several advanced concepts, including:

• MSRD (Mobile Station Receive Diversity)
• SAIC (Single Antenna Interference Cancellation)
• MUROS (Multi User Reusing One Slot)
• VAMOS (Voice services over Adaptive Multi-user channels on One Slot)

Furthermore, significant improvements have been made to EGPRS2 (Enhanced GPRS Phase 2), with the addition of 16 modulation-coding schemes in the downlink and 13 in the uplink. These EGPRS2 enhancements were introduced in 3GPP Release 7.

Key Technologies in GSM Advanced

• MSRD: Employs two antennas at the mobile station to combine signals, effectively eliminating significant interference. This is also referred to as DAIC (Dual Antenna Interference Cancellation). This technology improves both bit rates and spectrum efficiency.

• SAIC: Introduced in 3GPP Release 6, SAIC (Single Antenna Interference Cancellation) is another interference mitigation technique. Learn more about GSM SAIC.

• DARP (Downlink Advanced Receiver Performance): MSRD is part of the DARP-II requirement, while SAIC is part of the DARP-I requirement.

• MUROS: MUROS (Multi User Re-using One Slot) is a key feature in GSM Advanced that boosts the capacity for both voice and data services. This technique leverages orthogonal sub-channels, allowing two users to share the same time slot and ARFCN.

• VAMOS: Similar to MUROS, VAMOS was introduced in 3GPP Release 9. Refer to VAMOS basics for a more detailed explanation.