Measurement and Analysis of Spectrum Utilization for GSM/3G Mobile Communications in Metropolitan Taipei

• Main Authors: Cheng-Yuan Lee, 李政遠
• Other Authors: 張時中
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/90955500783601189326

碩士 === 國立臺灣大學 === 電機工程學研究所 === 97 === In recent years, because the demand for mobile communication service has increased rapidly,the existing fixed frequency spectrum distribution policy is not appropriate anymore. According to the U.S. FCC survey report [FCC03], the spectrum utilization has huge variation from 15% to 85% due to different time slots and geographic locations.The inefficiency could be solved by the support of “Dynamic Spectrum Access” which offers the potential to adapt to traffic dynamics and utilize spectrum efficiently [FCC03]. The main purpose of the thesis is to assess whether there’s an opportunity for the GSM/3G spectrum to be utilized by DSA in metropolitan Taipei.The research first puts emphasis on discussing the potential secondary spectrum market’s available spectrum.Furthermore,it will evaluate trends of future emerging mobile/wireless communication spectrum services and applications.With the discussion of the relationship between the demand and supply of the frequency spectrum,we can achieve the goal of studying whether there’s room for dynamic spectrum access in metropolitan Taipei. In this thesis,the hardware devices comprise spectrum analyzer and omni-directional antenna.In order to measure the spectrum utilization,we designed a set of methods for spectrum utilization measurement and created an environment for it.The experiment variables include:(1)spectrum band (based on Taiwan’s future policy of spectrum redistribution.(2)location (based on the users demands).(3)time (based on the frequency of spectrum use). Measurement index includes spectrum utilization and spectrum idle duration distribution；The resulting data will be compared with the power threshold value by using the Matlab analysis software to discuss the following issues:(1)The relationship between spectrum utilization and GSM/3G bands；(2)The relationship between spectrum utilization and locations；(3)The relationship between spectrum utilization and times；(4)The relationship between spectrum idle duration distribution and GSM/3G bands；(5)The relationship between spectrum idle duration distribution and locations；(6)The relationship between spectrum idle duration distribution and time.Moreover,in order to be in control of spectrum utilization change in all time intervals during one day, we set each sampling period for 32 seconds, which means 2,700 periods in total within one day and measured uninterruptedly. The results of the experiment are as follows:(1)The average spectrum utilization of 3G is between 20% to 45% in four different locations,with the highest spectrum utilization taking place in MRT(44%).(2)Spectrum utilization of 3G has subtle change at different time.(3)In terms of spectrum utilization of 3G,the downlink is perspicuously higher than the uplinkin different band.(4)Spectrum utilization of GSM is between 50% to 90% on average in the different locations,with the lowest taking place in NTU(60%).(5) Spectrum utilization of GSM changes from the offpeak time interval utilization(13.3%) to the peak time interval utilization(90%) in the different time intervals.(6)GSM has asymmetric traffic between uplink and downlink in different band.(7)There’s a spectrum interval of 16 seconds at least to 57 minutes at most that’s available for communication service within offpeak and peak.(8)In terms of spectrum supply,3G spectrum(150MHz) has more bands for other spectrum technology to use than GSM(16MHz). Based on the above analysis,we can find that GSM spectrum is used more frequently than 3G spectrum in terms of band, location and time.It seems that mobile users are used to 2G technology for wireless communication, which causes 3G wireless mobile spectrum underutilized.On the other hand,the future demand of wireless mobile communication will be broadband oriented, high-speed oriented and multi-access oriented(EX:WiFi+WiMAX,WiFi+WiMAX+3G,GSM+3G..etc.). In summary,3G bands have at least 70Mhz of available bandwidth at any time and location,which no doubt is a good news to wireless mobile communications since spectrums supplies are getting short.Though present GSM spectrum band has fine spectrum utilization (50% ~ 90%),there is still a small gap to fully utilization.To solve this problem,we can follow the Europeans who allow 3G services development in the 900MHz band while transferring part of the 3G business to GSM bands.On one hand, it can complement the existing GSM spectrum hole, making higher utilization of the spectrum; on the other hand it will provide more 3G bandwidth for broadband access and diversity technology use in the future.All in all, we believe that there is room for the development and application of dynamic spectrum access technology in metropolitan Taipei.