Frequency look-ahead and link state history based interference avoidance in wireless picocellular networks

In this paper, we present a scheme for combating the problem of interference in frequency hopping indoor wireless communication systems such as Bluetooth. Other methods in reported literature involve adapting the hopping sequence to avoid bad frequencies but they are unsuitable for Bluetooth which has a fixed hopping sequence for a picocell. The proposed scheme is based on the concept of frequency look-ahead and maintaining link state history (LSH) as a table. Look-ahead is employed to know a priori the frequencies that might be used for transmission in the near future. LSH is used to predict the probability of future interference. The paper gives two methods of recording LSH, the first based on the receipt of ACKs and NAKs from the slave and the second based on slave side monitoring of the channel. Before transmitting, the master checks the LSH table to select the slave and the packet size to transmit, such that both the transmissions to and from that slave have a low probability of error. By choosing the right packet size, the master is able to mask bad frequencies and does not need to change the hopping sequence in any way.