SAIC: Single Antenna Interference Cancellation in GSM

This page describes SAIC, which stands for Single Antenna Interference Cancellation Technique, used in GSM DARP enabled phones.

It explains the generic modules in a SAIC receiver and covers the different types of SAIC algorithms.

In GSM, SAIC refers to the Single Antenna Interference Cancellation technique. It was introduced in 3GPP Release 6. As the name suggests, the SAIC technique employs a single antenna along with interference cancellation/suppression. This primarily helps improve the receiver performance of GSM enabled DARP-I compliant mobile devices/UEs.

SAIC Advantages

• Due to performance improvement in the receiver part of the mobile/UE, GSM BTS needs to transmit less power compared to non-SAIC phones.
• SAIC mobiles will have lower FER (Frame Error Rate) compared to non-SAIC mobile phones.
• The single antenna makes it easier to integrate with the mobile phone PCB and contributes to a smaller phone size.

SAIC Algorithms

There are two main SAIC algorithms:

1. Blind Interference Cancellation (BIC): This technique focuses on the desired signal and is “blind” to the interferer signal. It’s applicable to GMSK modulated signals used in GSM systems. GMSK is mainly used for voice/GPRS applications.

2. Joint Demodulation (JD): This technique is used for 8-PSK modulation.

The technique used in MIMO (Multiple-Input Multiple-Output) systems is referred to as MAIC (Multi Antenna Interference Cancellation). DARP-II enabled mobile phones usually use MSRD (Mobile Station Receiver Diversity) technique.

SAIC Receiver Block Diagram

Fig.1

As shown in the SAIC receiver block diagram, after timing estimation and correction, interference is estimated using an auto-regressive filter. Later, I/Q whitening converts the colored noise in the signal to white noise before it’s applied to the channel estimation/equalization module.