EC-GSM: Advantages and Disadvantages of Extended Coverage GSM

This page explores the benefits and drawbacks of EC-GSM (Extended Coverage GSM).

What is EC-GSM?

Introduction: EC-GSM IoT stands for Extended Coverage GSM for Internet of Things. It adheres to the 3GPP Release 13 specifications and is categorized as one of the Low Power Wide Area (LPWA) technologies. It operates on licensed spectrum, similar to traditional GSM.

The EC-GSM physical layer incorporates new logical channels specifically designed for extended coverage. Furthermore, repetitions are used to provide the necessary robustness to support up to 164dB MCL (Maximum Coupling Loss). Overlaid CDMA (Code Division Multiple Access) is employed to increase cell capacity, particularly for EC-PDTCH (Extended Coverage Packet Data Traffic Channel) and EC-PACCH (Extended Coverage Packet Associated Control Channel).

It provides extended coverage, approximately 20 dB better than standard GSM. EC-GSM IoT and legacy GSM/GPRS traffic are dynamically multiplexed.

The following table summarizes the key features of EC-GSM technology:

Benefits or Advantages of EC-GSM

Here’s a breakdown of the advantages of EC-GSM:

• Long Battery Life: Offers battery life exceeding 10 years with a 5 Wh battery.
• Lower Device Cost: Reduces device costs compared to existing GSM/GPRS devices.
• Variable Rates: Utilizes variable rates using GMSK (Gaussian Minimum Shift Keying) / 8PSK (8-ary Phase-Shift Keying), similar to GSM. Supports rates from 350 bps to 70 Kbps with GMSK, depending on coverage extension. Achieves up to 240 Kbps using 8PSK.
• High Subscriber Capacity: Supports a high number of subscriber terminals, approximately 50,000 per cell.
• Improved Security: Enhances security compared to GSM/EDGE using GE4/5. It also inherits security and privacy features from mobile networks, including mutual authentication, confidentiality, and data integrity.
• Faster Time to Market: Leverages the maturity of GSM/GPRS for faster deployment and lower costs.
• Extended Coverage Range: Supports a coverage range of approximately 15 km.
• Efficient Resource Usage: Stores and utilizes coverage level information in the SGSN (Serving GPRS Support Node) to avoid unnecessary repetitions over the air.
• Power Saving Modes: Supports power-saving modes like eDRX (extended Discontinuous Reception), offering up to 52 minutes of sleep time, compared to GSM’s DRX with a maximum of 11 minutes.
• Easy Deployment: Can be easily deployed using existing GSM spectrum without impacting network planning. Existing GSM/GPRS base stations can be upgraded using software enhancements.

Drawbacks or Disadvantages of EC-GSM

Here are the limitations of EC-GSM:

• Limited Inter-RAT Support: Optimized system information but lacks inter-Radio Access Technology (RAT) support.
• Relaxed Idle Mode Behaviour: Features relaxed idle mode behaviour, such as reduced monitoring of neighbor cells.
• No Voice Support: Supports SMS (Short Message Service) and data but does not support voice calls.
• Low Throughput & Narrow Bandwidth: Supports approximately 10 Kbps throughput and uses a narrow frequency band. The system isn’t designed for high data throughput.