Description
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Electronic wireless communication is transmitted with the use of ElectromagneticFrequency Spectrum (Goldsmith, 2006). It is a unique natural resource shared byvarious types of services which is free from depletion but subject to congestionthrough use. It has facilitated a sequence of revolutions in human communication.Although, if left unplanned, spectrum congestion can lead to harmful interferenceand hinder users from getting the best these services have to offer. Traditionally,spectrum band is allocated relatively over a long period of time for the use of alicenseoperator.The use of radio spectrum in each country isnationallyregulatedbyassignedgovernmentagencywhichisresponsible for allocating spectrum bands to operators. In Nigeria, the NigerianCommunications Commission (NCC) is responsible for allocation of spectrum (Aibinu et al., 2015).This approach is termed the Fixed Spectrum Allocation (FSA) scheme. With this,the radio spectrum is split into bands and allocated on absolute basis to distincttechnologybasedservices,e.g.mobiletelephony,radioandTVbroadcastservices. In this work we are going to consider radioandTVbroadcastservices which are FM broadcast and Digital Video Broadcast.
The FM radio band is from 88 to 108 MHz; FM broadcasting is a method of radio broadcasting using frequency modulation. frequency modulation (FM) of the radio broadcast carrier wave was in 1933 by American engineer Edwin Armstrong, wide-band FM is used worldwide to transmit high-fidelity sound over broadcast radio. FM broadcasting offers higher fidelity—more accurate reproduction of the original program sound. Worldwide, the FM broadcast band falls within the VHF portion of the radio spectrum. 87.5 to 108.0 MHz (Aibinu et al., 2015).
Digital Video Broadcasting is a common standard for digital television and video used in many parts of the world. DVB standards include DVB-T for terrestrial television, DVB-C for cable television, and DVB-S for satellite television. Terrestrial digital TV broadcasting is a enables the viewer to receive higher quality video and audio signals than conventional analog TV, with no ghost images and no noise (Akbaret al., 2017).
Digital Video Broadcasting – Terrestrial (DVB-T) is a standard set in 1997 and put into use in 1998 for the transmission of digital terrestrial television (DTT). DVB-T is able to transmit different kinds of data, including compressed digital information, digital audio, digital video, Moving Picture Experts Group (MPEG) and other data with codec modulation. DVB-T provides an advanced method of transmission compared to the previous analog transmission.
Electromagnetic interference (EMI) is the major factor that affects both FM band broadcasting service and digital video broadcasting – terrestrial. Electromagnetic interference (EMI) is a disturbance generated by an external source that affects an electrical circuit. This disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data(Akbaret al., 2017).
EMIincommunicationsystemsismainlycausedbyunwantedvoltagesorcurrentwhichaffecttheperformance of communication system (Akyildiz et al., 2017) and manifested as noise. Different sources of EMI have beenidentifiedbutmainlycanbecategorizedintotwowhichareduetonaturalsourceslikelightning,electrostaticdischarge,atmosphericeffects,sunspotactivity,andreflectionsfromtheroughEarthsurfaceorman-madesourcessuchasindustrialactivity,hightensionelectriccables,radar,highpowerbroadcastingtransmitters (Akyildiz et al., 2017).
1.2 STATEMENT OF THE PROBLEM
A means of providing radio broadcasting services by using Frequency Modulation (FM) technique is called FM Broadcasting. Digital Video Broadcasting – Terrestrial (DVB-T) is a broadcasting service that is able to transmit different kinds of data, including compressed digital information, digital audio, digital video, Moving Picture Experts Group (MPEG) and other data with codec modulation. DVB-T provides an advanced method of transmission compared to the previous analog transmission. This services need to be offered under frequency interference free environment for ensuring quality receptions. However, different studies have shown that there exist frequency interferences on these services which are caused by Frequency Modulation (FM) and digital video broadcasting – terrestrial (DVB-T). Electromagnetic interference on both system causes degraded performance, disruption in communications and noise to the receivers(Akyildiz et al., 2017).
Electromagneticinterference (EMI) in communication systems is one of the major challenges whichface the communication sector and is mainly caused by unwanted signals which can be characterized asnoise. Due to this during communication system design stages, implementation phase and operation ofcommunication link Electromagnetic compatibility (EMC) measures are of great importance.
In other to solve this problem, there is need for mitigation measures. Mitigation measures or techniques involve process for making designchanges or adjustments of the signal or noise levels in order to achieve electromagnetic compatibility(EMC)areofgreaterimportance [6]. Performances of different electromagnetic interference (EMI) mitigation techniques were analyzed in this work.
1.3 AIM AND OBJECTIVES OF THE STUDY
The aim of the study is to carry out the performance analysis of mitigation technique for electromagnetic interference between FM band broadcasting service and Digital video broadcasting terrestrial (DVD_T).
The objectives of this work are:
- To analyze different mitigation techniques
- To determine performance analysis of different EMI mitigation techniques was based on Signal – to – Interference-plus – Noise Ratio (SINR) metric as a criterion.
- To improve FM band broadcast service and digital video broadcasting terrestrial signals
- To make recommendations on how FM band broadcast service and digital video broadcasting terrestrial signals can be improved.
1.4 SCOPE OF THE STUDY
The scope of this work covers the performance analysis of mitigation technique for electromagnetic interferance between FM band broadcasting service and Digital video broadcasting terrestrial (DVD_T).
Performances of different Electromagnetic Interference (EMI) mitigation techniques were analyzed by simulation method using Python, a high level multipurpose programming language. Performance analysis of different EMI mitigation techniques was based on Signal – to – Interference-plus – Noise Ratio(SINR) metric as a criterion.
1.5 SIGNIFICANCE OF THE STUDY
This study will provide a means of having a deep knowledge of FM band broadcasting service and Digital video broadcasting terrestrial (DVD_T).
This study will serve as a means of understanding the effect of electromagnetic interferance on broadcasting services.
Hundreds of urban centers across the nation are already deploying wireless broadcasting service which provides broadband access to residents. Mitigating interference could increase the quality of service. More so, it will enhance public safety communication; that is to say that public agencies can have access to spectrum in transmission band; this would improve the capacity and quality of their networks, as well as facilitate their expanded use for consumer services.
This study will serve as means of providing adequate protection to the broadcasting service and the primary users, taking into account current technologies. This dissertation shall extend into employing geolocation with access to data base and multi agents, which shall help record valid information about the available frequencies.
1.6 DEFINITION OF TERMS
FM broadcasting: This is a method of radio broadcasting using frequency modulation (FM). FM broadcasting offers higher fidelity, or more accurate reproduction of the original program audio. It’s also less susceptible to common forms of interference. FM is therefore used for most music and general audio (within the audio spectrum) broadcasts. FM radio stations use radio frequencies in the very high frequency range.
Digital Video Broadcasting – Terrestrial: DVB-T is able to transmit different kinds of data, including compressed digital information, digital audio, digital video, Moving Picture Experts Group (MPEG) and other data with codec modulation. DVB-T provides an advanced method of transmission compared to the previous analog transmission.
Electromagnetic interference (EMI): This is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning.
Broadcast Band:A broadcast band is a segment of the radio spectrum used for broadcasting. broadcast band.
Frequency Modulation, or FM: This is a type of modulation that conveys information by varying the frequency of a carrier wave.
Bandwidth: The bandwidth of an FM transmission is the sum of twice the maximum deviation and twice the maximum modulation frequency. For a transmission with RDS, this would be 2 x 75 kHz + 2 x 60 kHz = 270 kHz. This is also called the desired bandwidth.
CHAPTER FIVE
SUMMARY, CONCLUSION AND RECOMMENDATION
5.1 Summary
In this dissertation, a window-based application was developed and implemented on Java Run Time Environment (JRE) platform that performs spectrum management. Genetic algorithm was employed as the optimization technique for optimum allocation of free white space store questing WSDs.
Four locations were analyzed and proper sensing technique was used to find out the availability of white space in those environments. The result shows that there were over 60% available channels unutilized in each location under consideration amounting to a total about 1064 MHz available spectrum in the four locations.These available frequencies can comfortably serve requesting WSDs. ApacheDer by was used to design the database which is the most important aspect of this work because the information about the free spectra and location were housed by the database in a real time form to avoid the problem of false detection which can cause serious interference on the communicating devices.
ThespectrumsensingabilityontheTVWSwasimprovedbecausethedissertation was able to determine at every second the free spectrum holes and allocate devices to such holes.The dissertation also considered the need for continues communication between devices moving from one location to anotherandwiththeinformationprovidedbyrealtimedatabaseswitchingintofreespectrum holes was made possible. Among other things the dissertation was able to make provisions for the information to be provided by the device to the
database(s). The information returned from the database(s) to the device, The frequency of update of the database(s) and hence the periodicity with which devices will need to re-consult. The modeling algorithms and device parameters to be used to populate the data base(s) was also made possible.
5.2 Conclusion
After researching in TVWS and implementing a geolocation database technique with rule base and genetic algorithm, it can be concluded that it will be very profitable (both economically and in terms of communications QoS) alternative to traditional static communications, solving the lack of spectrum issue at the same time.
Analyzing the results from the database system, it has been demonstrated thatputting extra efforts and time in developing a detailed and complete initial design,its later implementation can be simplified considerably. In this way, we do notrequire large amount of resources and infrastructure, being the results quite good.Thesmallamountofnecessaryresourcesforitsimplementationmakesthegeolocation technique system a good candidate for commercial developments.However, it should be noted that with more detailed propagation models usingterrain data, the required computing resource will become higher. This will alsoleadtobetterutilizationof whitespacesandtomoreaccurateandtrustableresults.
It should be noted clearly that geolocation technique systems are in their initialdevelopment steps and in consequence just the basic functions have been defined.In the future and withthe experience, severaladditionalfeatures could be addedto the basic functionality of the system, improving QoS and efficiency. However,the dissertation successfully achieved the its scope, the state of art the art ofcognitiveradio,TVWSandcommunicationwasfirstanalyzedanddeepknowledgeonthesubjectwasacquiredanditsavailabilityinourlocality
ascertained. This knowledge was used to successfully implement a geolocationdatabasetechniquewithinvolvementofrulebaseandgeneticalgorithmforproperwhitespacedetectionandallocation.Forpublicaccesstotheimplementationandtoenableusersaccessthesystemfromanylocation,aprovisionforuploading ofthesystemasanapplettothe web wasalsoprovided.
5.3 Recommendation
This software is recommended to Federal Communications Commission (FCC)who on November 4, 2008, formerly approved the use of unused spectrum for WSDs. It is also recommended to Google who offered to host the database of available channels (sorted by latitude and longitude) free of charge. Also to Nigeria Communication Commission (NCC) that communication industries in Nigeria rely on their policies.
5.3.1 Areas of Application
The areas of application for deployment of this dissertation are
Many services and applications could benefit from this research work, they include:
- Wireless low power networks for hot spots and premises in TV bands, as an alternative to the highly congested industrial, scientific, and medical (ISM)band.
- Regional-area networking, especially suited to providing Internet in areas with poor wire line infrastructure.
- Hot-spot coverage: To provide communications in hot-spots similar to Wi-Fi technology used in public areas.
- Machine-to-machine communications: To provide communications between devices for purposes of control and remote monitoring of electricity meters that is smart metering.
- WirelessSurveillanceSystem:Toprovidevideosurveillanceandtrafficmonitoring
- 3G/4G networks extension over TVWS, complementing licensed spectrumusage:inparticularinfemtocellstominimizeinterferencetoownmacrocells.
- Radio transmission station with white space devices utilizing their channels,when the irradius of coverage is out side the transmitting range
- Traffic management and control (Vehicle to vehicle, Vehicle to Roadside broadcast device Vehicle to central broadcast database.
5.3.2 Suggestion for Further Research
After completing this research, it is possible to further extend the optimization of TVWS research in different other ways:
- The main security purpose of the database system is to ensure that the WSDs receive information from the validated database administrator and that no-one is trying to impersonate it sending invalid information. In the database system implementation, security features were not taken into consideration. However,in real database systems it is essential to develop several security measures such as user authentication (through interfaces with WSDs and Other users),Public key infrastructure (PKI), transport security (Since the interfaces can be defined as HTT Pinter faces carrying XML contents,thetransportlayersecuritycanbeperformedinthesamewayasinwebpagesprovidingauthentication, integrity and confidentiality (TLS, SSL), privacy, encryption etc. Future work should focus on developing the lacking security features of the geo-location database system.
- Alargescalechannelutilizationmeasurementcampaignacrosstimeandlocation is needed in order to better understanding how the open spectrum is utilized.
- For a better visualization of the benefit of cognitive radio, which is a major player in TVWS utilization a video streaming application can be added on top of the existing architecture.
- Other variables, such as transmission range,transmission rate, and packet size can also be tuned adaptively to optimize connectivity performance.
5.3.3 Review of Achievements
The TV White Space Optimization Software (TWHISO) produced has been tested and found to achieve the following:
Discovering of unused channels: One of the prevailing problems in spectrum management is the method of allocation that has made spectrum look scarce because of increase in the need wireless device. In this dissertation, alternative way of serving some wireless devices has been discovered through the use of UHF channels in the terrestrial television bands.
Interferencereductionbetweencommunicationdevices:Thespectrummanagementandallocationusinggeolocationtechniqueinthisdissertationreduced the possible occurrence of interference. This was done by making sure that optimal fitness is not adjacent to primary user and occupied channel. If adjacent the system assign a value of which indicate that it is not fit for allocation. If not adjacent the system assign a 1 meaning it is fit for allocation without interference.
Optimal allocation of TVWS to WSDs:The dissertation was able to achieve
this due to the nature of the algorithm used, the inference rules were well chosen which was used to form the knowledge base. The system communicates with the
knowledge base and all necessary conditions are tested before declaring a channel fit for allocation to WSDs.
Continuity in communication by WSDs: There is continuity in communicationbetween the WSDs. This is being made possible because of the switching abilitythedissertationoffers.WhenaWSDistransmittingandmovestoanotherlocation, it‟s transmitting channel changes from location A to location B. onlocation B the WSD is automatically switched to available channel in its newlocation.
Protection ofprimaryusers:With the combination ofgeolocation techniqueand sensing, the licensed user of the spectrum is protected with more accuracythan using sensing alone. This dissertation employed geolocation technique withsensing for maximum protection of licensed user of the spectrum. White SpaceDevices (WSD) arein constant interactionwith the database tomake sure thatanyharmfulinterferenceisavoided.
Providingchannelinformation:Thedissertationprovidedinformationonthelist of frequencies that could be used within each location. In order to allowvariable size bandwidths to be used the dissertation also provided start and endfrequencies which are considered more appropriate. In addition the maximumtransmit power was provided for each frequency assignment. Thiswould allowthe devices to operate accordingly in order to minimize the possible interferenceortoincreasetheflexibilityofthedevice.
Increase in spectrum Access: Spectrum access to white spaces would enhancespectrumutilization,whilealsotestingtheapproachofcontrollingtheinterferencebetweendifferentsystemsdirectlyratherthanthroughthetransmission power. The amount of interference generated to the license holdercan be controlled by our sensing model capabilities and geolocation databaseaccess.
Hybridcombination:Manypreviousresearchesinthisdomaineitherusesensing techniques alone in detection of spectrum holes or employ the use of geolocation database to identify list of available spectrum holes. This dissertation extended the research by taking into consideration the two separate entities intooneforoptimumresult.Theuseofgeolocationtechniqueandsensingindetermining the spectrum holes and protecting the primary users has optimized spectrum usage.
5.3.4 Benefits of the System
The following are the benefits of this dissertation
LongRange:TVWSarefoundintheVHFandUHFTVbroadcastingfrequencies, especially between 474−866 MHz as found in our analysis. At lowerfrequencies, radio signals have a very long range. As a result, fewer base stationsarerequiredforprovidingthesamelevelofcoverage,resultingincheapernetworks as this reduces both capital expenditure on network equipment andnetwork maintenance and operation (e.g. power for base stations) costs. Longsignal range is beneficial especially for providing coverage in rural areas, wherethealternativesolutionsareexpensive.
Better Speeds: The frequencies used for television broadcasting were chosen inthefirstplacebecausetheyweregoodattransmittinginformationquickly.Whereas Wi-Fi can shuttle data at 160-300 megabits (Mbps) per second, white-spacecandosoat400-800Mbpspersecond.
In-BuildingPenetration:TheexcellentpropagationofTVWSradiosignalsprovidesdeepin-buildingcoverage,allowingubiquitous(ornear-ubiquitous)coverage.Theirnon-line-of-sightperformanceofferstheabilitytopenetrateobstaclessuchastrees,buildingsandruggedterrain.
Free, Unlicensed Spectrum: TVWS are being opened up for new uses on a freeandunlicensedbasis.RegulatorsareconsideringorhavealreadyallowedTVWS
devices to operate in the TV band provided that they do not cause interference totheprimary spectrumusers.Freespectrumsignificantly reducesthecostsofoperatingwirelessnetworks.
IncreasingEconomicandSocialDevelopmentoftheCountry:Properimplementation of TVWS will open up mobile broad and allow for more datausage with the following benefits more productive farming (e.g. through onlineaccess to key information), a stimulus to the development of local e-commercebusinesses, enhancing delivery of teaching and training materials to rural schoolsand reducing the cost of health care delivery. Communication with distant familymembers will be enhanced – for example through video communication – and itwillbeeasiertokeepincontactthroughonlinesocialnetworks.
Globally harmonized spectrum: TV bands are harmonized worldwide, so whitespace can be expected tobe available globally. Having a global marketplaceofferstheprospectofeconomiesofscalefornetworkequipmentanddevices.This will spur the development of common standards and technologies whileallowingmanufacturerstomass-produceequipmentdrivingdownunitcosts.
Furthermore, recent developmental trends in wireless technologies are not only providing various opportunities for entrepreneurs, butal so over hauling the character of entrepreneurship by pioneering new business models. To date, anarray of competing wireless technologies have entered the market and these range from Wireless Mesh technology,WiFi,WiMAX(802.16),Cellular such as Universal Mobile Telecommunication Services/Wide band Code Division Multiple Access (UMTS)/WCDMA and High speed Down link Packet Access(HSPDA), Long-Term Evolution (LTE) and Advanced LTE. To this end, among these developments in the market, wireless meshnet works (WMNs), have in disputably and justifiably been touted as a candidate technology that is set to facilitate ubiquitous connectivity to the end user in under privileged,under
provisioned, and remote areas. The WMNs comprise wireless routers and clientsas well as an endowed ability to dynamically self organize, and self configure totheextentofnodesinthenetworkbeingabletoestablishandmaintainconnectivity among themselves. The candidature of this technology justifiably emanates from its characteristic low upfront cost, ease of maintenance, robustnessas well as reliable service coverage. Indisputably, WMNs have found applications ranging from broadband home networking, community and neighborhood networks, enterprise networking, building automation and other public safety areas etc. However, while the currently deployed WMNs provide flexible and convenient services to the clients, the performance, growth and spread of WMNsis still constrained by several design limitations such as limited usable frequency resource. The design constraints are a consequence of WMNs in the unlicensed Industrial, Scientific and Medical (ISM) band being mostly adopted for access communications. Subsequently this adoption renders the WMN susceptible tocompetitionwithallotherdevicesinthisparticularISMbandeg.nearbyWLANSandBluetoothdevices.Ultimately, the limited band width of the unlicensed bands cannot cope with the evolving network applications and this has led to the spectrum scarcity problem. However, with the discovery of TVWS and proper method of assignment to unlicensed device will provide an opportunity to significantly enhance the performance of WMNs and other wireless technologies.This will no doubt bring a lot of innovations like fostering hundreds of small scale incremental innovations due to the low costs involved.
5.4 Contributions to Knowledge
The following are the contributions to knowledge from this dissertation
- It provides a spectrum sensing model that can find the exact location ofprimaryuserandovercomethenumerouschallengesfacedbypresentspectrumsensingmethodswithinterferenceminimized.
- With the discovery of TVWS and availability within our locality for possible use by WSDs. This will spur entrepreneurs‟ to establish companies and improve the economic standard of our country since smart devices and equipment can easily connect to these available channels in an unlicensed manner reducing the overhead cost of running such organizations/industries.
Thedevelopedprograminthisdissertationwasabletoovercomefalsedetection and misdetection of spectrum holes by improving on spectrum sensing ability using geolocation techniques and a combination of rule base and genetic algorithm to give optimal utilization of the available spectrum spaces.
