Game Theory in Communication Networks
Encyclopedia
Game theory has recently become a useful tool for modeling and studying interactions between
cognitive radio
Cognitive radio
A cognitive radio is a kind of two-way radio that automatically changes its transmission or reception parameters, in a way where the entire wireless communication network -- of which it is a node -- communicates efficiently, while avoiding interference with licensed or licensed exempt users...

s envisioned to operate in future communications systems. Such terminals
will have the capability to adapt to the context they operate in, through possibly power and
rate control as well as channel selection. Software agents embedded in these terminals will
potentially be selfish, meaning they will only try to maximize the throughput/connectivity of
the terminal they function for, as opposed to maximizing the welfare (total capacity) of the
system they operate in. Thus, the potential interactions among them can be modeled through
non-cooperative games. The researchers in this field often strive to determine the stable
operating points of systems composed of such selfish terminals, and try to come up with a
minimum set of rules (etiquette) so as to make sure that the optimality loss compared to a
cooperative - centrally controlled setting- is kept at a minimum.

Applications of Non-Cooperative Game Theory in Wireless Networks Research

Game theory has been used extensively in wireless networks research to develop understanding of stable operation points for networks made of autonomous/selfish nodes. The nodes are considered as the players. Utility functions are often chosen to correspond to achieved connection rate or similar technical metrics. The studies done in this context can be grouped as below:

Medium Access Games for 802.11 WLAN

Various studies have analyzed radio resource management problems in 802.11 WLAN networks. In such random access
Random access
In computer science, random access is the ability to access an element at an arbitrary position in a sequence in equal time, independent of sequence size. The position is arbitrary in the sense that it is unpredictable, thus the use of the term "random" in "random access"...

 studies, researchers have considered selfish nodes, who try to maximize their own utility (throughput) only, and control their channel access probabilities to maximize their utilities.

Power Control Games in CDMA systems

Power control
Power control
Power control, broadly speaking, is the intelligent selection of transmit power in a communication system to achieve good performance within the system. The notion of "good performance" can depend on context and may include optimizing metrics such as link data rate, network capacity, geographic...

 refers to the process through which mobiles in CDMA cellular settings adjust their transmission powers so that they do not create unnecessary interference to other mobiles, trying, nevertheless, to achieve the required Quality of Service
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...

. Power control can be centralized in nature, where the base station dictates and assigns transmitter power levels to mobiles based on their link qualities, or they can be distributed, in which mobiles update their powers autonomously, independent of the base station, based on perceived service quality. In such distributed settings, the mobiles can be considered to be selfish agents (players) who try to maximize their utilities (often modeled as corresponding throughputs). Game theory is considered to be a powerful tool to study such scenarios.

Coalitional Game Theory in Wireless Networks

Coalitional game theory is a branch of game theory that deals with cooperative behavior. In a coalitional game, the key idea is to study the formation of cooperative groups, i.e., coalitions among a number of players. By cooperating, the players can strengthen their position in a given game as well as improve their utilities. In this context, coalitional game theory proves to be a powerful tool for modeling cooperative behavior in many wireless networking applications such as cognitive radio networks, wireless system, physical layer security, virtual MIMO, among others.
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