1	  	  	  Optimizing a Cooperative Relay NetworkUsing Advanced Power Allocation andReceiver Diversity Technique	  	  	  Muhammad H. D. Khan*, Muhammad D. Khan**, Mohammed S. Elmusrati*	  *Communication and System Engineering Group, University of Vaasa, Wolffintie 34, 65200, Vaasa, Finland**National University of Science and Technology, Islamabad, Pakistan.
hazandanish@yahoo.com , moel@uwasa.fi,	  	  Abstract—Cooperative relaying is a relatively new technique in wireless communication systems that make use of all the nodes present ina wireless sensor network by dynamically sharing their radio resources in a distributed manner. All the nodes present in the periphery of thetwo communicating nodes will act as relays and forward the information until it reaches the recipient node. By doing this, it achieves asignificant diversity gain, which in turn increases the robustness of the communication system. The diversity gain offered by cooperative
relay transmission can only be exploited fully if a receiver diversity technique is being employed at the recipient node. Moreover, theses
cooperative relay networks inherit the power limitation of a traditional wireless sensor network. Therefore, in this paper an effort has been
made to optimize a cooperative relay system by addressing these two issues. First, node powers expressions will be derived for a 3-nodeconfiguration using fixed gain amplify and forward protocol over a Rayleigh Fading Channel. Second, performance of a 3-nodeconfiguration has been further analyzed by using different receiver diversity techniques at the destination node. Simulation results arepresented to validate the performance gains when advanced power allocation and receiver diversity is employed in a cooperative relay
network.
Keyword—Cooperative relay network, Maximal ratio combining, Moment generating function, Diversity techniques, Rayleigh fading
channel, Fixed gain amplify and forward.	  	  	  Muhammad H. D. Khan (S’13) was born in Rawalpindi, Pakistan, in 1986. He received the B.E. degree in electrical engineering fromthe COMSATS Institute of Information Technology, Islamabad, Pakistan, in 2010, and the M.Sc. degree in technology from University ofVaasa, Vaasa, Finland, in 2013.
In 2010, he joined the Department of Avionics Engineering, Air University, Pakistan, as a Research Assistant, and in 2011 became aResearch Associate. His current research interests include wireless communication systems, sensor networks and resource allocationmanagement.	  	  	  Muhammad D. Khan (S’14) was born in Islamabad, Pakistan, in 1992. He received the B.E. degree from the National University ofScience and Technology (NUST), Islamabad, Pakistan, in 2013. In 2013, he joined the Department of Electrical Engineering, NUST,Pakistan, as a Researcher. His current research interests include Communication systems and Signal Processing.	  	  	  	  	  	  	  	  	  Mohammed Elmusrati (S’00-M’04-SM’12) received the B.Sc. (with honors) and M.Sc. (with high honors) degrees in telecommunicationengineering from the Electrical and Electronic Engineering Department, Benghazi University, Libya, in 1991 and 1995, respectively, andthe Licentiate of Science in technology (with distinction) and the Doctor of Science in Technology degrees in control engineering fromAalto University - Finland, in 2002 and 2004, respectively. Currently, Elmusrati is full professor and head of communications andsystems engineering group at University of Vaasa - Finland. Moreover, Elmusrati has Adjunct Professor position at Automation andSystems Technology Department at Aalto University. Elmusrati is a member of the Automation Society of Finland. Elmusrati has
published more than 70 peer reviewed papers and reports. Moreover, he is coauthor for a textbook “SystemsEngineering in WirelessCommunications” Wiley 2009. His main research interests include Radio resource management in wireless communication, wirelessnetworked control, game theory, and smart grids.