Relay Assisted Cooperative Ambient Backscatter Communication With Hybrid Long-Short Packets

In this paper, we investigate a relay-assisted cooperative ambient backscatter communication network, where the primary transmitter (PT) and the backscatter transmitter (BT) transmit a long packet with an infinite blocklength and a short packet with a finite blocklength to an information receiver (IR) with the aid of a relay node, respectively. Considering the energy causality constraint and the decoding error in the process of successive interference cancellation (SIC), we derive the expressions for PT's outage probability and BT's average block error rate (BLER). The analytical results show that the fixed SIC decoding scheme considered at IR may lead to a poor performance for both the outage probability and the average BLER. To address it, we propose an improved SIC decoding scheme and evaluate its achievable transmission performance by deriving the expressions for PT's outage probability and BT's average BLER. Computer simulations verify our derivations, confirm the superior performance of the improved SIC decoding scheme compared to the fixed one, and provide insights into the influences of different parameters (e.g., PT's transmission power, BT's power reflection coefficient, power allocation of the relay node) on the achievable outage probability and average BLER. Particularly, increasing the short-packet blocklength enhances the BLER performance of BT. However, it does not necessarily improve the outage performance of PT.