Bandwidth Allocation for Multiple- User and Multiple- Relay Cooperative Systems Using Stackelberg Game

Abstract

While dealing with wireless communication systems (whether infrastructure based systems that have one controlling entity known as access point, or ad- hoc systems), the nodes present can be fixed at a location or can be moving from one coverage area to another. With this randomness, the channel conditions between the users always changes due to different paths followed by signals to reach from one user to another. Due to multiple paths, several mechanisms can occur in between the source and the destination due to the surroundings like reflection, scattering, diffraction, or Doppler Effect. These mechanisms lead to multiple copies of a single information signal, and due to mainly destructive interference at the receiver fading occurs which degrades the quality of signal. To combat this fading effect, several diversity techniques are employed namely time diversity, frequency diversity, spatial diversity, etc. Out of the above mentioned diversity techniques spatial diversity technique is the most suitable form as it doesn’t require any extra frequency bands or time intervals, but it comes with a disadvantage too of more complex hardware requirement which is not handy. To avoid these problems, a new diversity technique has been introduced in literature which is known as cooperative diversity technique. This technique provides the advantage of spatial diversity without actually introducing new antennas. The users which are already present in the system helps each other to forward the information hence relaying each other’s information. This technique hence gives the benefit of Multiple Input Multiple Output (MIMO) technique virtually. The users however may be willing to help without need of a profit or may be selfish in nature. This work focuses on allocating the most important as well as the limited resource required essentially for the communication purpose i.e. Bandwidth. So, a two- level Stackelberg Game is introduced in the work according to which the nodes which are helping in relaying are termed as leaders or vendors that sell their bandwidth to the users which are in need of transmission of information and the users hence become followers or purchasers who pay charges for buying bandwidth slots. The Stackelberg Equilibrium hence solves the problem of which relays should be selected, what charges they should demand from the users and which users should be given the bandwidth by allocating the optimal bandwidth and optimal prices. Further, the difference is found out between the resource allocation done in distributive and in a centralized way in which it is proved that the distributed method is actually better in allocating the resources than the centralized one.