Optimization of Packet Length for Two Way Relaying with Energy Harvesting Ghassan Alnwaimi *,Hatem Boujemaa **, Kamran Arshad *** (*) King Abdulaziz University, Kingdom of Saudi Arabia (**) University of Carthage, Sup’Com, COSIM Laboratory, Tunisia (***) College of Engineering, Ajman University galnwaimi@kau.edu.sa,boujemaa.hatem@supcom.tn, k.arshad@ajman.ac.ae May 16, 2019 Abstract In this article, we suggest optimizing packet length for two way relaying with energy harvesting. In the first transmission phase, two source nodes N 1 and N 2 are transmitting data to each others through a selected relay R. In the second phase, the selected relay will amplify the sum of the signals received signals from N 1 and N 2 . The selected relay amplifies the received signals using the harvested energy from Radio Frequency (RF) signals transmitted by nodes N 1 and N 2 . Finally, N 1 will remove, from the relay’s signal, its own signal to be able to decode the symbol of N 2 . Similarly, N 2 will remove, from the relay’s signal, its own signal to be able to decode the symbol of N 1 . We derive the outage probability, packet error probability and throughput at N 1 and N 2 . We also optimize packet length to maximize the throughput at N 1 or N 2 . Index Terms : Cooperative systems, Optimal packet length, Rayleigh fading channels. 1 Introduction In Two-Way Relaying (TWR), two nodes N 1 and N 2 simultaneously transmit data to each other using a selected relay [1-5]. The communication process contains two phases. In the first one, N 1 and N 2 transmit data to some relays. Each relay will receive the sum of signals transmitted by N 1 and N 2 . In the second phase, a selected relay amplifies the received signal. Then, N 1 will remove, from the relay’s signal, its own signal to be able to decode the symbol of N 2 . Similarly, N 2 will remove, from the relay’s signal, its own signal to be able to decode the symbol of N 1 . Two way relaying for Multiple Input Multiple Output (MIMO) systems has been con- sidered in [1-5]. Receive and transmit diversity improves the performance of TWR. At the receiver, the best antenna can be selected (Selection Combining SC). The corresponding International Journal of Computer Networks & Communications (IJCNC) Vol.11, No.3, May 2019 DOI: 10.5121/ijcnc.2019.11307 97