Game theoretical analysis of Resource Allocation in Cooperative Communication

Abstract

In wireless communication the electromagnetic waves propagate through multiple paths towards the destination which in turn induces variation of strength of the signal received at destination. These rapid fluctuations in signal strength are called fading which can be combat by implementing diversity in space, time, and frequency in wireless communication. Spatial diversity requires multiple antennas, placed at some specified distance from one another, to transmit same signal to the common destination. The multiple antenna deployment for small size, hand held devices is not possible which leads to introduction of cooperative diversity.Cooperative diversity is a diversity technique in which nodes relay signals for each other. The node uses other nodes to transmit its signal to destination. Without deploying actual multiple antenna the nodes form a virtual multiple input multiple output system which we be used to enjoy the benefits of diversity and combat fading effects. The basic principle of cooperative communication is based on broadcast nature of the wireless communication. Whenever a node transmits, it broadcast its signal in all direction which not only reaches the destination but is also overheard by the nearby nodes which act as a relay for the source.Cooperative communication helps in combatting fading by reducing the dependency of wireless system on the quality of particular path. It provides transmission reliability and signal strength improvement. It increases the throughput as compared to direct transmission. It increases the link performance, can help in overcoming the shadow effect and thus provide better coverage area. The main two objective of wireless communication is to find best relay out of all the relay available and proper resource allocation among the nodes. These decisions can be made by using the decision making criteria called game theory. Game theory is a decision making theory which considers nodes as a player which compete with one another to win the game. The game uses utility function as a factor to decide which player wins the game. The player follow strategy to attain maximum or optimal utility value. The game theory can be used to make decision using Shapley value. Shapley value is the easiest, less complex technique to make decision in game theory. The Shapley formulae is the weighted sum of marginal contribution of each player in a coalition. The value obtained by the player decides the resource allocation in cooperative game model.