LAUSR

Reconfigurable intelligent surface (RIS) has been proved effective in improving the performance of communications. In this letter, the effect of RIS on individual links in ambient backscatter communications is examined. The average bit error rate is derived for the cases when the source-to-reader (S-R) link, the source-to-tag (S-T) link, or both S-R and S-T links use RIS to enhance their links. Numerical results show that generally speaking the performance of ambient backscatter communications degrades when the number of RIS elements in the S-R link increases, while improves when the number of RIS elements in the S-T link increases, when RIS is used to enhance the relevant link. Also, the two effects cancel out but in general the performance improves when both links are enhanced by RIS.