Usama Mir

A Cooperative Multiagent Based Spectrum Sharing

A major issue in recent wireless networks is the static utilization and allocation of the available spectrum. An effective solution to this problem is to detect the empty spectrum portions using cognitive radio devices and to share them with the neighboring users, in a dynamic and distributed manner. However, since nodes generally have limited knowledge about their environment, we suggest that cooperative behavior can provide them with the necessary information in order to solve the global issues. To this extend, we develop a novel approach for spectrum allocation using multiagent system cooperation that enables cognitive radio (or secondary user) devices to utilize the amount of available spectrum, dynamically and opportunistically. The key aspect of our design is the deployment of agents on each of the primary and secondary user devices that cooperate in order to have a better use of the spectrum. For cooperation, contract net protocol is considered, allowing spectrum to be dynamically allocated by having a series of exchange of messages amongst the devices. Simulation results show that our approach achieves up to 80% of the whole utility within the span of few messages, and provides an effective mechanism for distributed spectrum allocation.

A continuous time Markov model for unlicensed spectrum access

Recent static spectrum allocations have created an opportunity to develop novel solutions that can efficiently share the available spectrum both in licensed and unlicensed bands. Considering the relative rarity of solutions for unlicensed spectrum access, in this paper, we propose a scheme, where the cognitive radio (CR) devices (equipped with agents) interact with their neighbors to form several coalitions over the unlicensed bands. These types of coalitions can provide a less-conflicted spectrum access as the agents mutually agree for spectrum sharing. Further, we present a continuous time Markov chain (CTMC) with queuing to model the user interactions with the movement of spectrum access process from one state to another and derive the important performance metric as the blocking probability. Numerical results are presented to observe the impact of forming multiple coalitions on the blocking probability.

Multiagent Based Spectrum Sharing Using Petri Nets

This paper presents a cooperative framework for dynamic spectrum access in cognitive radio networks, where the cognitive radio devices may use the currently unutilized spectrum dynamically and opportunistically. The proposed solution works on the principle of multiagent system that allows the cooperation amongst several participating devices. The key aspect of our design is the deployment of agents on each of the primary and cognitive radio device that cooperates in order to have a better and dynamic use of the spectrum. For cooperation, contract net protocol is considered allowing spectrum to be dynamically allocated by having a series of exchange of messages. Due to the concurrent, distributed and autonomous nature of our approach, Petri nets are adopted to model the behavior of cooperative framework. Based on Petri nets, we study the internal message passing and spectrum allocation mechanism between the participating primary and cognitive radio users and identify the information needed by the agents to make cooperative decisions. Then, using empirical results, we show that our approach achieves up to 80% of the whole utility within the span of few messages, and provides an effective mechanism for distributed spectrum allocation.

Utilization of a Cooperative Multiagent System in the Context of Cognitive Radio Networks

In this paper we propose an approach to solve the spectrum allocation/sharing problem using Multiagent System (MAS) cooperation that enables Cognitive Radio (CR) devices to share the unutilized spectrum dynamically and opportunistically. We introduce briefly the problem of static spectrum assignment and propose an approach to solve this issue. The key aspect of our design is the deployment of agents on each of the CR and Primary User (PU) devices that cooperate in order to have a better use of the spectrum. An example scenario is also presented along with our proposed model.

COMAS: a cooperative multiagent architecture for spectrum sharing

Static spectrum allocation is a major problem in recent wireless network domains. Generally, these allocations lead to inefficient usage creating empty spectrum holes or white spaces. Thus, some alternatives must be ensured in order to mitigate the current spectrum scarcity. An effective technology to ensure dynamic spectrum usage is cognitive radio, which seeks the unutilized spectrum portions opportunistically and shares them with the neighboring devices. However, since users generally have a limited knowledge about their environment, we claim that cooperative behavior can provide them with the necessary information to solve the global issues. Therefore, in this paper, we develop a novel approach for spectrum allocation using a multiagent system that enables cognitive radio devices to work cooperatively with their neighboring licensed (or primary user) devices in order to utilize the available spectrum dynamically. The fundamental aspect of our approach is the deployment of an agent on each device which cooperates with its neighboring agents in order to have a better spectrum sharing. Considering the concurrent, distributed, and autonomous nature of the proposed approach, Petri nets are adopted to model the cooperative behaviors of primary and cognitive radio users. Our simulation results show that the proposed solution achieves good performance in terms of spectrum access, sustaining lower communication overhead.

A Markov Process for Dynamic Spectrum Access

In order to increase the efficient spectrum usage and to mitigate the current spectrum scarcity, dynamic spectrum access is considered to be an emerging technique. In this paper, based on the concept of dynamic spectrum access, we propose a Markov process that models the two-way interaction process between a primary and a cognitive radio user for dynamic spectrum usage. Several probabilities and matrices of response, no-response, agreement and no-agreement for a spectrum sharing process are derived. Numerical results are then shown to explore the impact of key systems parameters like users arrival rates on the derived probability of response.