Use of the Recursive Least Squares Filter for Self Interference Channel Estimation

Abstract

This paper presents the use of recursive least squares for online estimation of the self interference channel for an In Band Full Duplex communications link without the use of half duplex pilot signals. By using a long effective filter length it is possible to overcome the extra interference of the receieved signal, and it proves to be an effective way to estimate the channel in all scenarios, but it provides the greatest efficiency gain over current methods with a short channel coherence time. Recursive least squares estimation provides a way to take advantage of the constant knowledge of the transmitted signal to track the channel while consuming relatively few computational resources. Introducing online RLS estimation for In-Band Full Duplex communication provides a way to take advantage of the self interference cancellation gains from digital cancellation without introducing additional protocol overhead to the transmissions.