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An Insight into Spectrum Occupancy in Nigeria

Bara’u Gafai Najashi1*, Feng Wenjiang2 Choiabu Kadri3

1College of Communication Engineering, Chongqing University,

Chongqing, China, Postal Code 400044

174 Shazheng Street, Shapingba District, Chongqing







AbstractAbstractAbstractAbstract

The rapid evolution in wireless communication which hasled to the development of several standards has alsobrought about a perceived spectrum scarcity. Studies haveshown that contrary to popular belief concerning spectrumscarcity, most of the allocated spectrum is heavilyunderutilized. This has led to several spectrum occupancymeasurements mostly in the US, Europe and recently Asiato ascertain the utilization level of the allocated spectrum.These measurements will help in determining which bandswill be suitable for the deployment of cognitive radiotechnology. In this paper, an indoor spectrum occupancymeasurement conducted within the region of 700 MHz to2.5 GHz in Abuja, Nigeria is presented. The resultsobtained indicate that large portion of the allocatedspectrum is underutilized which could be considered for thedeployment of cognitive radio paradigm in the near future.

KeywordsKeywordsKeywordsKeywords: Cognitive radio, spectrum occupancy, wirelesscommunication, Abuja

1.1.1.1. IntroductionIntroductionIntroductionIntroduction

The rapid development of wireless standards andbandwidth hungry technologies has led to a perceivedshortage of spectrum. In order to satisfy the growingdemand for new spectrum, the spectrum managementpolicy needs to be changed. Currently, the

administrative or command and control approach tospectrum management has proven to be ineffective[10]. Several spectrum occupancy measurementscarried out all over the world [2-9] mostly in USAand Europe with very few found in Africa havebuttressed the fact that the assigned spectrum bandsare underutilized. The idea of sharing the spectrumbetween a primary user (PU, the entity the spectrumwas assigned to) and a secondary user (SU, the userthat uses the spectrum opportunistically withoutinterference)by using dynamic spectrum accesstechniques is what mainly cognitive radio is allabout[7].The concept of Cognitive radio was firstintroduced by Mitola [1] in 1999. He describedcognitive radio as a smart radio that has a fullunderstanding of its environment and can also adaptits operating parameters to adapt to changes in theenvironment. The importance of spectrum occupancymeasurements cannot be underestimated. Theknowledge of the utilization level of the spectrumbands will help researchers to conceive (devise)spectrum models that could be used to predict futureutilization. It could also help policy makers indetermining which bands have low occupancy: thiswill go a long way in determining the bands that aresuitable for dynamic spectrum access. Spectrum

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usage is dependent on location, time, measurementconditions, and equipment [2]. While spectrummonitoring tends to provide detailed information onconformity with laid down rules pertaining spectrumusage which a spectrum planner uses to ascertain thelevel of compliance and also to confirm theeffectiveness of current planning system, spectrummeasurements on the other hand tend to quantify theperformance of the measuring band. It should benoted that the utilization level of a particular bandcannot be extended to other bands or other locations[11]. In [3], Kishor Patil et. al conducted a spectrumoccupancy measurements in the frequency band from700MHz to 2700MHz in an outdoor scenario insuburban Mumbai, it was found that the spectrumoccupancy of the entire band to be roughly 6.62%. In[12], a measurement campaign was performed inGuangdong province in china which also showed alow occupancy. Shared Spectrum Company hasperformed many measurement campaigns in severalAmerican cities which also showed low spectrumoccupancy. [4] De Francisco, R et al. and MiguelLopez-Benitez et. al performed spectrum occupancymeasurement in Netherlands and Spain respectively.The results were similar to what was obtained inother campaigns. [5,6]. Other measurementsconducted [7-9] also proved that the spectrumutilization level is low.

In this paper, a spectrum occupancy measurementwas performed in the region of 700MHz-2.5GHz in apredominantly residential district of Abuja, Nigeria.The measurements were conducted indoors and thebands with low utilization levels were identified.Each band was monitored for 12 hours daily. From 9am to 9 pm. The statistics obtained can also provevaluable to policy makers in managing this preciousresource.

The remainder of the paper is organized as follows;in section II the equipment used in the measurementsetup are described. In section III we shall present theresults obtained from the measurements and analysisof those results. Section IV concludes this paper andsuggests potential future research areas.

2.2.2.2. MATERIALSMATERIALSMATERIALSMATERIALS ANDANDANDANDMETHODMETHODMETHODMETHOD

2.1 Measurement Setup

The measurement setup used consists of an AaroniaAG HF-6060 V4 spectrum analyzer with a range of10MHz-6GHz, an Aaronia AG OmniLOG 90200antenna with a range of 700MHz to 2.5GHz, a laptopsystem that is connected to the spectrum analyzer via

a USB cable, and an MCS software speciallydesigned to run on Aaronia AG spectrum analyzers.The setup is connected as shown in figure 1.MATLAB software package was used to process andanalyze the data and the results presented in latersections.

FigureFigureFigureFigure 1111: Setup used for measurement

2.2 Location

The measurement was conducted indoors atGwarinpa District a primarily residential district inAbuja, Nigeria. These measurements were conductedindoors as part of larger measurement campaignwhich we hope will provide an insight into theutilization level of the spectrum in Nigeria. Abuja islocated at with a population of about 770,000 as at2006. The measurements were taken from 9 am to 9pm a duration of roughly 12 hours. The spectrumanalyzer settings employed in this work are given inthe table 1

PARAMETERPARAMETERPARAMETERPARAMETER VALUEVALUEVALUEVALUESpan 200MHz/300 MHzTiming 500 msResolution(samples) 51Bandwidth Filter 200 KHzVideo Filter 200KHzTableTableTableTable 1111: Spectrum Analyzer Parameters used in conducting themeasurement

2.3 Decision Threshold

In spectrum occupancy measurements, determiningthe decision threshold upon which a particularchannel can be deemed as free or busy is veryimportant especially when energy detection isemployed. In energy detection, no prior knowledge ofthe signal is known therefore it’s very important tocorrectly determine the threshold for accurate



readings. Setting the threshold metric too high willlead to under estimation of the spectrum while lowdecision metric will lead to over estimation of thespectrum. The normal convention is to keep thedecision metric some certain dB above theequipment’s noise floor level. The noise floor for thesetup was obtained by replacing antenna with a50ohm resistor we can similarly measure the noisefloor by removing the antenna and not replacing itwith anything[]. In this work, a threshold of -76 dBmwas used after the two methods were tested.

2.3 Spectrum allocation in Nigeria

Nigeria can be said to be arguably the leadingcountry in Africa as far as spectrum deregulation andlicensing are concerned. Since 1992, over 350broadcasting licenses have been issued by theNigerian Broadcasting Corporation (NBC) and over300 licenses issued in the telecommunication sectorby the Nigerian Communication Commission (NCC)[16]. Policy formulation and management ofspectrum in Nigeria is determined by the severalbodies. These include National FrequencyManagement Council, the Ministry of Informationand Communication, Nigerian CommunicationCommission, and the Nigerian BroadcastingCorporation:

NationalNationalNationalNational FrequencyFrequencyFrequencyFrequency ManagementManagementManagementManagement CouncilCouncilCouncilCouncil: TheNational Frequency Management Council (NFMC) isthe apex body for radio frequency spectrummanagement in Nigeria. Established by Section 26 ofthe Nigerian Communications Act 2003 and locatedwithin the Ministry of Information &Communications, NFMC is the primary sponsor andinfluence on the Government’s frequency spectrumpolicies and legislation. The Council is responsiblefor the planning, coordination and bulk trans-sectoralallocation of radio spectrum to the regulatory bodies,namely the National Communications Commission,the National Broadcasting Commission and theMinistry, and acts as the focal coordinator of allfrequency spectrum activities in Nigeria. The Councilalso advises the Minister on Nigeria’s representationat international and multi-lateral frequency spectrumbodies. NFMC is chaired by the Minister ofInformation & Communications and consists of high-level representatives of the Ministries of Aviation,Transport, Science & Technology, NCC, NBC andthe Security Services, and meets at least four times ina year [17]

NigerianNigerianNigerianNigerian CommunicationsCommunicationsCommunicationsCommunications CommissionCommissionCommissionCommission: NCC isthe regulator of the telecommunications industry andhas wide discretionary powers to plan, manage,

assign and monitor the use of spectrum bycommercial users of telecommunications services.The roles of NCC also includes: the encouragementof competition; the removal of market entry barriers;interconnection of new operators with incumbents;the monitoring of tariffs and quality of service; theprotection of consumer rights; and the overallpromotion of affordable telecommunications services.The Commission develops and publishes radiofrequency regulations and standards for the industry.

NationalNationalNationalNational BroadcastingBroadcastingBroadcastingBroadcasting CommissionCommissionCommissionCommission: TheCommission derives its powers from the NBC Act 38of 1992 as amended by the National BroadcastingCommission Act 55 of 1999 and is the sole bodycharged with regulating the broadcast industry,setting broadcast standards and upholding equity andfairness in broadcasting. NBC assigns broadcastfrequencies it receives from NFMC to private &public radio & TV stations, monitoring forcompliance with administrative procedures, thebroadcast code and technical standards. NBCprocesses applications for the ownership of all typesof radio and television stations and has licensed over350 operational stations in several categoriesincluding private, public, satellite, network, campusand community radio & TV stations. TheCommission regulates broadcasting through 27 state& zonal offices and regularly publishes updates ofthe radio frequencies it assigns on its website [16].

MinistryMinistryMinistryMinistry ofofofof InformationInformationInformationInformation &&&& Communications:Communications:Communications:Communications: TheMinistry, through the Department of SpectrumManagement, is responsible for the formulation andmonitoring of communications policies, internationaltreaties and national representation in internationalorganizations, including the InternationalTelecommunication Union (ITU), International CivilAviation Organization (ICAO), InternationalTelecommunication Satellite Organization (ITSO),International Maritime Organization (IMO), amongothers. With the establishment and increasedlegislative empowerment of both the NCC and NBC,MoIC’s function has gradually been limited to themanagement and assignment of frequencies toGovernment and non-commercial users including themilitary, security services, diplomatic missions,voluntary organizations and non-profit groups. TheMinistry raises revenue for the Government throughthe sale of amateur radio communication licenseapplication forms, issuance and renewal of licenses,and type-approval testing of radio communicationequipment. MoIC is the secretariat of NFMC and actsas the custodian of all frequencies in Nigeria [16].



BANDBANDBANDBAND FREQUENCYFREQUENCYFREQUENCYFREQUENCYRANGERANGERANGERANGE

USAGEUSAGEUSAGEUSAGE ANDANDANDANDPLANPLANPLANPLAN

800 MHz 790 – 806 Trunk RadioServices

900 MHz 890-960 MHz GSM1 GHz 1.35-1.525,1.579-1.772

1.805-1.91,1.96-1.99GHz

Rural Telecoms,GSM, Oil coy.Satellitebroadcast, radionavigationservices.

2 GHz 1.99-2.11,2.2-2.285,2.305-2.32,2.345-2.36,2.4- 2.5GHz

3Gmobiles ,wirelesslocal loop, satelliteup/downlink,scientific,industrial andmedicalapplications

TableTableTableTable 2222: Spectrum Allocation Table for some services in Nigeria.

RESULTSRESULTSRESULTSRESULTS ANDANDANDAND DISCUSSIONDISCUSSIONDISCUSSIONDISCUSSION

The first band considered was the 700-1000MHz. Itcomprises the 800MHz band used for trunk radioservices, emergency services, CDMA (fixed), 900MHz for GSM and also the 470-960 MHz foranalogue television broadcasting. [13]. In the VHFband there are 12 channels where as the UHFband consists of 49 channels making a total of61 channels [14]. This band has the highestutilization level experienced at 26% due to theactivities of the analogue broadcasting (part of it tobe precise) GSM operations and the radio trunkservices. CDMA technology employs the use ofspread spectrum where by the signal power is verylow almost the same with noise power. This makesthe signal difficult to detect by the spectrum analyzer.The utilization level could be much more than theobtained value due to this factor.

FigureFigureFigureFigure 2222: Power level in dBm versus frequency (700-1000 MHz)

FigureFigureFigureFigure 3333: Power level in dBm versus frequency (1.1-1.3GHz)

FigureFigureFigureFigure 4:4:4:4: Power level in dBm versus frequency (1.3-1.5GHz)

FigureFigureFigureFigure 5:5:5:5: Power level in dBm versus frequency (2-2.2GHz)



The 1000- 1500 MHz band is mostly used formicrowave point to point communication [1350-1550MHz], government agencies and oil companiesin the Niger delta region and Lagos [18].The 1000-1300 MHz and 1300-1500 MHz with a utilizationlevel of 2.13 and 1.85 respectively are among thebands with the lowest utilization level. Apart frommicrowave point to point transmission observedaround 1350-1450MHz; there is virtually no activityat all.

Above 1.5 GHz, majority of the utilization can beobserved in the 3G mobile standards. With autilization level of around 25.1% it has one of thehighest utilization level amongst the bandsconsidered for this work. In Nigeria, there arecurrently five mobile companies delivering 3Gmobile services in Nigeria: MTN, Globacom, Airtel,Etisalat and Starcomms [15]. Networks employingUMTS use WCDMA technology as stated above, thespread spectrum nature of the signals where by thesignals are modulated over a wide bandwidth thusmaking them having a noise-like character due to thevery low transmission power makes them difficult todetect. This makes it difficult for the spectrumanalyzer to determine such signals. Similarly, sincethe measurements’ were conducted indoors, theability of the antenna to receive signals might behindered.

Above 2.42 GHz, with 17% utilization, the ISM bandshows considerable utilization but it could alsoprovide some opportunity for secondary usage. Asthe measurement was done indoors it was able todetect much of the signals due to the short nature ofsignals in this band. Some activity on the satelliteuplink and downlink bands were also detected at afrequency of 2.305-2.32 MHz and 2.335-2.36 MHz

FigureFigureFigureFigure 6666: Waterfall of 1.3-1.5 GHz range



BLOCKBLOCKBLOCKBLOCK FREQUENCYFREQUENCYFREQUENCYFREQUENCYRANGE(MHz)RANGE(MHz)RANGE(MHz)RANGE(MHz)

DUTYDUTYDUTYDUTYCYCLECYCLECYCLECYCLE

1 700-1000 26%2 1000-1297.5 2.13%3 1297.5-1500 1.85%4 1500-1700 12.7%5 1700-1997 25.56%6 1997-2200 0.45%7 2200-2400 17.42%TableTableTableTable 3333: Summary of Spectrum Occupancy

CONCLUSIONCONCLUSIONCONCLUSIONCONCLUSION

In this work, an attempt was made to get thespectrum utilization level in Abuja the capital city ofNigeria. The 700-2500 MHz band was considered.The measurements were conducted indoors as part ofwider planned measurements to be conducted. Theresults indicate abundant potential for CRdeployment.. The cellular communication bands can



be said to possess the highest utilization level at 26%and 25.56% for the bands containing the 2G and 3Gcellular standards, while the 1000-1500 MHz and2000-2200 MHz bands have the lowest utilizationlevel as the results in table 3 indicate. These resultswill hopefully aid the academia and policy makers informulating future policies for spectrum management.In the near future, further measurements would betaken to obtain a realistic picture of the utilizationlevel. Similarly, measurements would be conductedin other locations both indoors and outdoors over alonger period of time to get a more detailed picture ofspectrum usage in Nigeria

REFERENCESREFERENCESREFERENCESREFERENCES

1. J. Mitola and G. Maguire, “Cognitive Radio:Making Software radios more Personal”,IEEE Personal Communications,13:70(1999), 13-18.

2. Soraya Contreas et. al, “An investigationinto the Spectrum Occupancy in Japan in theContext of TV White Space Systems”, 6thInternational Conference on CognitiveRadio oriented Wireless Networks andCommunications, 2011.

3. Kishor Patil, Ramjeed Prasad et. al,“Spectrum occupancy measurementstatistics in the context of cognitive radio”.IEEE 14th International Symposium onWireless Personal MultimediaCommunications (WPMC), 2011.

4. Shared Spectrum Company, “SpectrumOccupancy Measurements”, SharedSpectrum Company reports. Available athttp://www.sharedspectrum.com/measurements/.

5. De Francisco, R “Spectrum Occupancy inthe 2.36-2.4 GHz band: Measurement andAnalysis”, European Wireless Conference(EW), IEEE 2010.

6. Miguel Lopez-Benitez et. al. “Evaluation ofSpectrum Occupancy in Spain for CognitiveRadio Application”, IEEE 69th Conferenceon vehicular Technology. 2009

7. Salim A. Hanna et. al, “Spectrum metrics for2.4GHz ISM Band Cognitive Radio

Applications”, IEEE 22nd InternationalSymposium on Personal, Indoor, and MobileRadio Communications. 2011

8. Yanfeng Han et al. “Spectrum OccupancyMeasurement: Focus on the TV Frequency”,International Conference on SignalProcessing System, 2010.

9. Oliver Holland et. al, ”Spectrum PowerMeasurements in 2G and 3G Cellular PhoneBands during the 2006 Football World Cupin Germany”, New Frontiers in DynamicSpectrum Access Networks, 2007.

10. Linda E. Doyle, “Essentials of CognitiveRadio”, New York: Cambridge UniversityPress, 2009.

11. Zhe Wang, Sana Salous,”SpectrumOccupancy Statistics and Time seriesmodels for cognitive radio”, Journal ofSignal Processing System, Springer, 2009.

12. Dawein Chen, Sixing Yin et. al. “MiningSpectrum Usage Data: a large-scaleSpectrum Measurement Study”, IEEETransactions on Mobile Computing, 2009.

13. Gbenga Ilori, “Development of VHF andUHF Spectrum Optimization for digitalservices in selected states of Nigeria”,University of Ilorin PhD thesis 2010.

14. Gbenga-Ilori et al. “Nigerian BroadcastSpectrum Usage in the analogue and digitaldomain”, Proceedings of the NigerianInstitute of Electrical and ElectronicsEngineers (NIEEE), 5th Annual NationalConference, 2009.

15. www.ncc.gov.ng

16. Fola Odufuwa, “Open Spectrum forDevelopment Nigeria Case Study”,Association for Progressive Communication,2010.

17. www.nfmc.gov.ng

18. Nigerian Communication Commission,“Commercial Frequency ManagementPolicy and Technical Guidelines” January2007.



http://www.sharedspectrum.com/measurements/

http://www.sharedspectrum.com/measurements/

http://www.ncc.gov.ng/

http://www.nfmc.gov.ng/