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Master Program in

Communications Engineering

Institute for Networked SystemsPrinciples and Architectures of Cognitive Radios

Principles and Architectures of

Cognitive Radios

Homework #1

By: Irving Antonio Barra Castillo Matriculation number: 328023

HOMEWORK ASSIGNMENT .Student Review of J. Mitola and G. Maguire paper on Cognitive Radios.

In the present document, an important scientific paper written by Joseph Mitola III and GeraldQ. Maguire Jr. is summarized and reviewed. In general, the topic is cognitive radio technology

and also the data representation of important parameters for the radio. The paper was firstpublished in 1999, as part of the IEEE journal on personal communications.

The paper of Mitola and Maguire introduces a descriptive language for cognitive radios, which

is meant to enable the exchange of relevant communication parameters between radios inorder to operate according to the well-established etiquette, i.e., conventions of proper

usage of spectrum, power, etc. The writing starts with an interesting case of a GSM radio not

having even the possibility to determine its internal structure, for example, for the electronics

in charge of channel equalization. Even though the components and algorithms are there, the

radio lacks of a method to analytically represent what is happening in its insides. It is here

where the authors introduce the Radio Knowledge Representation Language or RKRL for

short, which they claim will make such description possible. The problem of modeling the

internals of the radio has not a strong focus in the paper; however from the semantics of the

language one can very well derive a suitable modeling strategy.

An interesting functionality mentioned in the paper is that cognitive radios could even trackthe users mobility in order to make adjustments accordingly, not only in the large scale, like

when moving to another continent, but also in the medium to small scale, for example whenthe user is traveling in a taxi cab around the city. Of course, the authors admit that this level of

complexity would also imply a requirement for high computing power.In order to properly make the point for the need of RKRL, the authors compare several

existing languages that could help in describing radio related parameters. The analysis then

shows that many of them do not completely fulfill the specific requirements of cognitiveradios, thus a new language is definitely required.

Using RKRL, radios would have the possibility to describe, interact and even anticipate or plantheir future behavior, all while respecting the rules of usage or radio etiquette(limitations

due to the laws of physics need to be considered as well). The authors use an interestinganalogy with a chess game, in which the radio becomes the player who has a view of the

board and can therefore plan ahead what movements could be done next according to the

rules of the game. This general view is one of the key aspects RKRL is meant to enable.The descriptions follow a hierarchical structure which, more or less like the hierarchy of

directories in a file system, but including also keywords to describe the relation between the

components of the hierarchy.

Cognitive radios could use RKRL as part of what the authors call cognitive cycle. During this

cycle, radios analyze the stimuli in their surroundings to determine their location andenvironmental conditions of operation (temperature, height, etc), so that they can make the

necessary adjustments in order to perform their intended task.

8/13/2019 Cognitive Radios - Excercise 1

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iNETS RWTH Aachen Irving A. Barra C.

Principles and Architectures of

Cognitive Radios2 Homework #1

Students comments on the paper:

During the first section of the paper, my personal impression is that the authors point is very

strong, especially because of the detailed example of the receivers equalizer where it really

shows that theres a need for something which allows the devices to indicate more detailed

information, not only regarding to measurements only but also the actual parameters used in

their operation. However, I think the approach they propose tends to be too ambitious andtries to cover so many aspects of this task that I can imagine that a real-world implementationof RKRL would only use a subset of the functionalities described in the paper.

The language and the possibilities are described to some extent; however as a formal

description of a new language, I would also expect to see in the paper some usage rules.

Also, the comparison with other languages or description mechanisms, thought useful, could

have been better by showing specific examples of how each one of them do the task, ratherthan the descriptive approach taken by the authors, in which a reader not familiar with the

other languages being compared can only believe the arguments without a more tangible

proof.

Regarding the specifics of the RKRL, some examples are given thorough the paper, however

the very description of the concept and the semantics is, at least for me, not so clear. The

general idea is really interesting in the context of cognitive radios because it seems that a

standardized language for the exchange of information related to communication parameters

is necessary and will definitely help to improve the performance and speed of adaptation. Had

the description of the RKRL been a bit clearer, I would say this paper was really good.

However, since some technical aspects were not too deeply explained and what they didexplain were ideas rather too futuristic, I think I would not put this paper in my top list.