FR (Enhanced Full Rate)

Introduction:

Enhanced Full Rate (EFR) is a digital speech coding algorithm, used in GSM (Global System for Mobile Communications) mobile networks, to compress voice signals for transmission over the airwaves. EFR provides improved voice quality and higher compression rates than the earlier used Half Rate (HR) and Full Rate (FR) codecs, while still maintaining backward compatibility with these codecs. In this essay, we will explore the technical aspects of EFR, its advantages, and its impact on mobile communication.

Background:

The GSM network was introduced in the 1980s, and it is still widely used for mobile communication. In the early years, voice calls were encoded using analog technology, which limited the capacity of the network. Later, digital speech coding algorithms were developed to compress voice signals, which allowed more voice calls to be transmitted simultaneously over the same frequency band. The HR and FR codecs were introduced to improve the capacity of the GSM network, but they had limitations in terms of voice quality and compression rates.

Enhanced Full Rate (EFR):

EFR is a speech coding algorithm that was introduced in the late 1990s, as an improvement over the HR and FR codecs. EFR uses a modified version of the Algebraic Code Excited Linear Prediction (ACELP) algorithm, which is a widely used speech coding algorithm. The ACELP algorithm uses a combination of linear prediction and codebook search to compress voice signals.

In EFR, the ACELP algorithm is modified to improve the quality of the compressed voice signals. The modifications include a larger codebook size, a longer frame length, and improved signal processing. These modifications allow EFR to achieve a compression rate of 12.2 kbps, which is higher than the 6.5 kbps and 13 kbps compression rates of the HR and FR codecs, respectively. The higher compression rate of EFR allows more voice calls to be transmitted over the same frequency band, which increases the capacity of the GSM network.

Advantages of EFR:

The main advantage of EFR is the improved voice quality that it provides. EFR has a higher compression rate than the HR and FR codecs, which allows it to capture more details of the voice signal. This results in clearer and more natural-sounding voice calls. The higher compression rate also reduces the amount of background noise and distortion in the voice signal, which further improves the quality of the call.

Another advantage of EFR is its backward compatibility with the HR and FR codecs. EFR can be used in mobile devices that support the HR and FR codecs, without requiring any hardware or software changes. This allows mobile network operators to upgrade their networks to support EFR, without needing to replace existing mobile devices. Backward compatibility also allows EFR to be used in areas where HR and FR codecs are still in use, which increases the coverage and capacity of the network.

Impact of EFR:

EFR has had a significant impact on mobile communication since its introduction. The improved voice quality of EFR has made mobile communication more enjoyable and productive for users. It has also made it possible to use mobile phones for tasks that require clearer voice communication, such as conference calls and voice recognition.

The higher compression rate of EFR has also had a positive impact on the capacity and efficiency of mobile networks. It allows more voice calls to be transmitted over the same frequency band, which reduces the need for additional network infrastructure. This reduces the cost of building and maintaining mobile networks, which can be passed on to users in the form of lower tariffs.

Conclusion:

Enhanced Full Rate (EFR) is a speech coding algorithm used in GSM mobile networks, to compress voice signals for transmission over the airwaves. EFR provides improved voice quality and higher compression rates than the earlier used Half Rate (HR) and Full Rate (FR) codecs, while still maintaining backward compatibility with these codecs. EFR uses a modified version of the Algebraic Code Excited Linear Prediction (ACELP) algorithm, which is a widely used speech coding algorithm. The modifications made to the ACELP algorithm in EFR allow it to achieve a compression rate of 12.2 kbps, which is higher than the 6.5 kbps and 13 kbps compression rates of the HR and FR codecs, respectively.

The advantages of EFR include improved voice quality, backward compatibility with HR and FR codecs, and increased capacity and efficiency of mobile networks. The higher compression rate of EFR allows more voice calls to be transmitted over the same frequency band, which reduces the need for additional network infrastructure and ultimately reduces the cost of building and maintaining mobile networks.