Unit 3 introduction to cognitive radios

1. RMK College of Engineering and Technology
EC6014
Cognitive Radios
Department
of
Electronics and Communication Engineering

2. Unit 3
Introduction to
Cognitive Radios

3. Syllabus
• Marking radio self-aware.
• Cognitive Techniques
• Position Awareness in cognitive radios
• Environment Awareness in cognitive radios,
• Optimization of radio resources
• Artificial Intelligence Techniques.

4. Problem with SDR
• These radios are designed to perform a task instructed by a software.

5. Lets Consider Your are Programmed for Driving

6. Same Applies to Radios as well

7. The Biggest Challenge….

8. “Learning” to Adopt is the only Solution

9. Once Learned Next is to “Think”

10. Cognitive Radios - Introduction
• Cognition is "the mental action or process of acquiring knowledge and
understanding through thought, experience, and the senses.

11. How to make radios Learn and Think

12. Cognitive radio - Definition
• A cognitive radio may be defined as a radio that is aware of its environment and
the internal state and with knowledge of these elements and any stored pre-
defined objectives can make and implement decisions about its behavior.

13. Why Cognitive Radios
Natural Resources scarcity

14. Electro magnetic spectrum

16. bodies work on standards for radio frequency allocation,
• International Telecommunication Union (ITU)
• European Conference of Postal and Telecommunications
Administrations (CEPT)
• Inter-American Telecommunication Commission (CITEL)

17. Radio frequencbroad y bands are divided into 3 categories:
• Frequencies that are not usable for commercial purposes and are kept reserved for radio
astronomy to avoid interference at radio telescopes.
• Frequencies that are unlicensed and are open for personal or commercial use for free which
includes 2.4GHz and 5GHz WiFi, Bluetooth, cordless phones, etc.
• Frequencies that are licenced by the government for purposes like telecommunication.

18. Telecommunication Regions

19. Telecommunications Regions
• Region 1: Europe, Middle East, Africa, the former Soviet Union, including Siberia;
and Mongolia
• Region 2: North and South America and Pacific (East of the International Date
Line)
• Region 3: Asia, Australia and the Pacific Rim (West of the International Date Line)

20. Deeper into radio spectrum
• The radio spectrum is the part of the electromagnetic spectrum from 3 Hz to 3000 GHz (3 THz).
• Electromagnetic waves in this frequency range, called radio waves, are extremely widely used in modern
technology, particularly in telecommunication.
• To prevent interference between different users, the generation and transmission of radio waves is
strictly regulated by national laws, coordinated by an international body, the International
Telecommunication Union (ITU).

21. Bands ….
• A band is a small section of the spectrum of radio communication frequencies, in
which channels are usually used or set aside for the same purpose.
• To prevent interference and allow for efficient use of the radio spectrum, similar
services are allocated in bands. For example, broadcasting, mobile radio, or navigation
devices, will be allocated in non-overlapping ranges of frequencies.

22. ITU’s Band allocation ….

23. ITU’s Band allocation ….

24. Spectrum Scarcity is the biggest problem ..

25. Cognitive Radio is the Solution..

26. Making Radios Self “Aware”
• 3 steps are important for making radio self aware
• Aware radios
• Adaptive radios
• Learning Radios

27. Aware radios
• One motivation for an aware radio is providing information to the user.
• As an example, an aware radio may provide a pull-down menu of restaurants within a user-defined radius.
• Another example of an aware radio is the code division multiple access (CDMA) based cellular system. This
system is aware of QoS metrics and makes reservations of bandwidth to improve overall QoS.

28. Adaptive radios
• The various operating parameters that can be adapted are Frequency,
instantaneous bandwidth, modulation scheme, error correction coding, channel
mitigation strategies such as equalizers or RAKE filters, system timing (e.g., a
time division multiple access [TDMA] structure), data rate (baud timing),
transmit power, and even filtering characteristics.

29. Adaptive radios - examples
• Example 1: A frequency-hopped spread-spectrum radio is not considered
adaptive because once programmed for a hop sequence, it is not changed.
• A frequency-hopping radio that changes hop pattern to reduce collisions may
be considered adaptive.

30. Adaptive radios - Examples
• Example 2: A radio that supports multiple channel bandwidths is not
adaptive, but a radio that changes instantaneous bandwidth and/or system
timing parameters in response to offered network load may be considered
adaptive.

31. Learning Radios
• A radio is said to be a learning radio or cognitive when they posses the following
characteristics
• Sensors creating awareness of the environment.
• Actuators to interact with the environment.
• A model of the environment that includes state or memory of observed events.
• A learning capability that helps to select specific actions or adaptations to reach a performance
goal.
• Some degree of autonomy in action.

32. FrameworkforSelfAwareCognitive
Radios
• When a radio tries to exchange the information among the various units to become
self aware, there comes a problem, that different units in the radio system contains
information in their own language which cannot be interpreted by other units.
• A radio that uses RKRL (Radio Knowledge Representation Language) to accomplish
the self awareness is illustrated in Figure.

34. CognitionCycle
• Cognitive radio learns about the environment through the process of
cognition cycle
• The cognition cycle presented in the figure summarizes the major steps
involved in the cognition process.

36. Major elements of Cognition Cycle
• The following 6 major elements constitute the Cognition Cycle:
• Environment: this includes the network and the surrounding environments such as
physical channels, other users, devices, networks, and any objects that may affect the
network conditions (e.g., weather conditions, obstacles, economic indicators and
trading rules).

37. Major elements of Cognition Cycle
• Sense: The different CR entities are capable of sensing and monitoring the
environment such as the spectrum bands, interference levels, physical
propagation channel parameters, and location of Primary Users and Secondary
Users.
• Plan: Secondary Users make plans and assess these plans before taking
decisions.

38. Major elements of Cognition Cycle
• Decide: Decision is based on knowledge and learning where the decision making
process optimises the system’s resources.
• Act: The secondary User will act on the environment based on the decision made. This
can be through a sequence of actions (e.g., access to the media, routing of packets,
allocation of resources, and modification of transmission schemes).

39. Major elements of Cognition Cycle
• Learn: Learning is the central element in the cognition cycle where the nodes are
equipped with a knowledge base and a learning tool that allows them to keep track
of all information related to the network and environment conditions. This allows
the system to learn from current and previous actions, predict future behaviours,
and intelligently use them in planning and decision making processes.

40. CharacteristicsofRadioCognitionTasks
LEVEL CAPABILITY TASK CHARECTERISTICS
0 Pre-programmed The radio has no model-based reasoning capability
1 Goal-driven Goal-driven choice of RF band, air interface, and protocol
2
Context
Awareness
Infers external communications context (minimum user
involvement)
3 Radio Aware Flexible reasoning about internal and network architectures
4
Capable of
Planning
Reasons over goals as a function of time, space, and context
5
Conducts
Negotiations
Expresses arguments for plans/ alternatives to user, peers,
networks
6 Learns Fluents Autonomously determines the structure of the environment
7 Adapts Plans Autonomously modifies plans as learned fluents change
8 Adapts Protocols Autonomously proposes and negotiates new protocols

41. CognitiveTechniques
Position awareness
Environment Awareness

42. Position Awareness
• A radio must primarily know its position and Time.
• From these information a radio can
• Calculate the antenna pointing angle
• Minimize the interference with other users
• Get help in navigation.
• Position and time are considered as essential elements for smart radio.

43. Positioning Systems
• Positioning systems plays an important role in several applications.
Aircraft
VHF Omni directional Ranging Systems
Ships
Long Range Navigation Systems (LORAN)

44. Well Known Positioning Systems

45. Global Positioning Systems
• GPS system is divided into three segments:
• Space Segment
• Control Segment
• User Segment

46. Space Segment
• There are normally 24 active GPS satellites located on
their orbits.
• These satellites are geometrically spaced in such a way
that 5 -8 satellites are visible at any specified point on
earth.
• A line of Sight Visibility is needed to process the
signal and calculate the location.

47. Space Segment

48. Control Segment
• Ground tracking stations are positioned worldwide to monitor and operate
the constellation of GPS Satellites.
• The stations monitors the satellites signals , process them and transmit back
to the space vehicles.
• These processed data are transmitted to the GPS Receivers.

49. User Segment
• The GPS Receivers acts as the User Segment.
• These receivers process the signals from four or more satellites into 3D
Position and time.

51. Network Localization

52. Example Case..
• A foreigner wants to watch a Movie at PALAZZO.
• What a normal GPS Result Looks like

53. Maximum.. he can reach the Forum Mall

54. Approaches for Geolocation
• There are several approaches to provide the accurate position awareness.
• Time Based Approaches
• Time of Arrival Approach (ToA)
• Time Difference in Arrival Approach (TDoA)
• Angle of Arrival Approach (AoA)
• Received Signal Strength Approach (RSS)
• Network Based Approaches

55. CR Architecture with Location and Environment Awareness
Engine.
• There are 4 important engines in
CR Architecture.
• Cognitive Engine
• Spectrum Awareness Engine
• Location Awareness Engine
• Environment Awareness Engine

56. Responsibilities of Various Engines
• Cognitive Engine - supervises the other engines in order to accomplish goal driven and autonomous
tasks.
• Spectrum Awareness Engine - is to handle all the tasks related to dynamic spectrum (e.g., acquiring
available bands, corresponding carrier frequencies, and bandwidths).
• Environment Awareness Engine - is managing environment information (e.g., number of paths,
corresponding path delays and coefficients).
• Location Awareness Engine is to handle all the task related to location information.

57. Location and Environment Awareness Cycles
• There are 3 main modules to be
discussed.
• Sensing Interface
• Location Awareness Engine
• Environment Awareness Engine

58. 1. Sensing Interface
Inspiring from the sensing features of the creatures.

59. 1.Sensing Interface
• Sensing process is composed of mainly two components, which are sensors and associated data post-processing methods.
• Sensors are utilized to convert the signals acquired from environment to electrical signals so that cognitive radios can
interpret.
• The acquired signals can be in different format such as electromagnetic, optic, and sound. Therefore, sensors can be
categorized under three types; electromagnetic, image, and acoustic sensors.
• Sensing interface is a common component in cognitive radios to interact with environment and other users, we focus on
the sensing methods for location and environment awareness systems.

60. Sensing Interface contd…
• The sensing mechanisms in cognitive radios are classified into three main
categories based on the type of sensors used.
• Radio Sensing.
• Radio Vision.
• Radio Hearing.

61. 1.1 Radio Sensing
• Radio sensing is a sensing technique utilizing electromagnetic sensors and the associated post-
processing Schemes.
• The most widely used radio sensing (electromagnetic) sensor in wireless systems is Antenna.
Antenna is a transducer that converts electromagnetic signal into electrical signals and vice versa.
• Location information is estimated from the received signal statistics such as Time-of-Arrival (TOA),
Receive Signal Strength (RSS), and Angle-of-Arrival(AOA).

62. 1.2 Radio Vision
• Radio vision is a sensing approach using image sensors
and the corresponding post-processing schemes.
• Radio vision sensor such as image sensor is a device that captures optic signals from the environment and converts them to
electrical signals in order to construct the corresponding image.
• Computer vision is a branch of artificial intelligence aiming to provide vision systems functioning like human vision in
computers. The recent advances in vision systems such as cognitive vision systems and scene analysis show the feasibility of
designing cognitive radios with vision capabilities.

63. 1.3 Radio Hearing
• Radio hearing is a sensing method employing acoustic
sensors and the associated post-processing schemes.
• Radio hearing is a sensing method employing acoustic sensors and the associated post-processing schemes.
• One of the radio hearing sensors is acoustic sensor ,which is a transducer that converts acoustic signals into
electrical signals and vice versa.
• For example, acoustic location estimation techniques(e.g. sonar – Sound Navigation And Ranging) can be utilized
for cognitive location-aware applications.

64. 2. Location Awareness Engine
• The location awareness engine consists of 3 subsystems
• Location Sensing
• Location Awareness Core
• Location Aware Algorithm Adaptation.

65. 2.1 Location Sensing
• One of the fundamental features of location awareness engine is to estimate the location
information of target object in a given format.
• The format of location information that needs to be sensed can have significant effects on the
complexity of location aware algorithms.
• There are 3 different location sensing techniques, they are as follows:
• Radio sensing method
• Radio vision method
• Radio hearing method

66. 2.2 Location Awareness Core
• The main objective of this core is to perform critical tasks related to location information such
as learning, reasoning, and making decisions.
• The core is composed of
• Seamless Positioning and Interoperability,
• Security and Privacy,
• Statistical Learning and Tracking,
• Mobility Management,
• Location-Aware Applications.

67. 2.2.1 Seamless Positioning and Interoperability.
• Seamless positioning is defined as a system that can keep the position accuracy
at a predefined level regardless of the changes in channel environment.
• There are mainly two approaches for achieving seamless positioning. They are as
follows,
• Waveform-Based Methods (Based on GPS)
• Environment Sensing-Based Methods (Based on RSS)

68. 2.2.2 Security and Privacy
• The user’s Location information has to be protected from unauthorised
intruders on the network.
• The first threat is violating the User Privacy.
• Second is that they may lead to catastrophic scenarios, since Location Based Services are
highly dependent on location information

69. 2.2.3 Location Aware Applications

70. 2.2.4 Mobility Management
• Utilization of location information in cognitive radio and networks for different applications will have major
impact on the system complexity. Introduction of such additional services and applications into cognitive
wireless networks will worsen the mobility issues. Consequently, the system capacity and implementation
cost can be affected by these issues.
• Therefore, it is desirable to develop an accurate mobility model during the network planning
phase. Therefore, the location awareness engine has a mechanism to handle mobility tasks

71. 2.3 Location Aware Algorithm Adaptation
• The main objective of the adaptation block is to supportlocation awareness engine in terms of adaptation
of algorithms and parameters for the satisfaction of the user, consequently, cognitive engine requirements. These
requirements stem from the autonomous location-aware applications that are supported.
• The various requirement of location-aware applications are accuracy, integrity, continuity, and
availability. Nevertheless, range accuracy is one of the most important requirements of location-aware applications,
Autonomous location-aware applications (e.g.advanced LBS) can require different level of accuracy.

72. 3. Environment Awareness Engine
• Environment awareness is one of the
most substantial and complicated task
in cognitive radios since channel
environment is the bottleneck of
wireless systems.

73. Few Questions that Arises are…
• The consequent essential questions that arise are:
• What type of information to acquire from environment?
• How to acquire such information?
• How to utilize the acquired environmental knowledge in cognitive radios and
networks?

74. Functionalities of Environment Awareness Engine
• The model consists of following functionalities:
• Environment awareness core
• Topographical information
• Object recognition and tracking
• Propagation characteristics
• Meteorological information
• Environment sensing
• Environment adaptation

75. 3.1 Topographical Information
• Topography is defined as ‘‘the science or practice of describing a
particular place, city, town, manor, parish, or tract of land; the accurate
and detailed delineation and description of any locality”.

76. 3.2 Object Recognition and Tracking
• Objects are defined as the human-made entities present in the target local environment
temporarily or permanently.
• The large and permanent human-made structures such as buildings and bridges are
considered as part of topography of environment
• On the other hand, relatively small and movable human made entities such as vehicles,
home and office appliances are considered as objects

77. 3.3 Propagation Charecteristics
• This entity provides information on the characteristics of signal progression through a medium
(channel environment).
• Basically, propagation characteristics of channel environment shows that how the channel affects the
transmitted signal.
• The statistical characteristics of wireless channel are describedmainly with two groups of statistics:
• Large-scale
• Small-scale

78. 3.4 Metrological Information
• This entity provides information on the weather of target local region,which can affect the signal propagation.
The current and future weather parameters such as rain, snow, temperature, humidity, and pressurecan be acquired either
using radio auxiliary sensors or from central cognitive base station.
• By having current and forecasted meteorological information, cognitive radio can adapt itself accordingly.
• For instance, rain can have significant affects on the performance of broadband fixed wireless access links (e.g. Fixed WiMAX),
especially operating at higher carrier frequencies

79. OptimizationOfRadioResources
• As discussed earlier CR uses AI to adapt and optimize the performance of
the radio platform.
• The question arises that which parameter to optimize?

80. Parameters for optimization
•Bit Error Rate
• Bit error rate (BER) is an important objective for all digital communications’ needs. It provides a
baseline for the amount of information transferred,
• BER calculations depend heavily on the type of channel and type of modulation, and
so the cognitive engine must know the formula for each modulation type the radio is capable of using
and the channel types it is likely to see during operation.

81. 2. Bandwidth
• Bandwidth is an objective that is also used in many other objective calculations.
• It appears in the bit error rate, interference power, spectral efficiency, and
throughput.
• It is a direct measurement of how much spectrum is occupied by the radios.
• This objective offers a good indication of the spectral resources occupied and therefore
measures the trade-offs we have been discussing.

82. 3. Spectral Efficiency
• Spectral efficiency represents the amount of information transferred in a given channel and is measured
in bits per second per Hertz (bps/Hz).
• Although this concept is directly related to both bandwidth and throughput, it contributes equally to the
quality of service
• Spectral efficiency helps shape the decision space by biasing the solution towards a symbol rate and
modulation type that provides high bandwidth efficiency and produces better data rates for given spectrum
availability.

83. 4. Interference
• The interference power is calculated over a given bandwidth
• The calculation of interference power is different than SINR from an objective
perspective: SINR helps the cognitive engine decide if it is good for the waveform
to transmit on this frequency.

84. 5. Signal to interference plus noise ratio (SINR)
• The signal to interference plus noise ratio (SINR) can inform the
cognitive radio about how the presence of interferers can affect the signal
reception

85. 6. Throughput
• Throughput is a measure of the amount of good information received.
• This definition distinguishes throughput from data rate in that data rate is
simply a measure of the rate at which data arrives with no consideration for
transmission errors.

86. 7. Power
• There are two ways to look at power as a resource.
• The first way is to think about power in terms of how the radio transmitter uses the external power in the
spectrum.
• In this manner of speaking, power is a shared resource by all radio nodes, so radios should strive to
reduce their transmission power.
• The second way to analyze power is to measure it in terms of power consumption by a radio.
• Each waveform consumes a certain amount of power that depends on the processes required to transmit
and receive information correctly.

87. 8. Computational Complexity
• This contributes to the second way of power optimization.

88. Dependency functions
• Solid Lines  Direct dependency
• Dashed Lines  Indirect dependency

89. ArtificialIntelligenceTechniques

90. Techniques…
• Neural Networks
• Markov Model
• Fuzzy Logic Systems
• Genetic Algorithms
• Case Based Learning

91. 1. Neural Networks
• is a network inspired by biological neural networks which are used to
estimate or approximate functions that can depend on a large number
of inputs that are generally unknown.

92. End
of
UNIT 3