Best traffic carrier frequency number and cell wireless utilization research

Transcription

1 Available online at Procedia Engineering 24 (2011) International Conference on Advances in Engineering Best traffic carrier frequency number and cell wireless research Zhi LIU 1, Zhenhong JIA 1, Xizhong QIN 1, Chun CHANG 2, Guojun XU 2, Xiaoyan XIA 2 1.College of information science and Engineering, Xin jiang University, Urumuqi , P.R China 2.Xinjiang Mobile Communication Company, Urumqi, Xinjiang , P.R China Abstract In order to solve the problems of unreasonable cell carrier frequency configuration (CCFC) and insufficient wireless resources in GSM network, the conception of the best CCFC number is introduced. By the statistical analysis of the large number of traffic data, find out the relationship between the CCFC and the busy traffic congestion rate, and then obtain the best carrier frequency configuration number in each traffic interval. According to the best carrier frequency configuration number, the best cell wireless rate is obtained. This standard reflects the demand number of cell actual carrier frequency configuration, which provides a theoretical basis for the CCFC and the current network cell wireless in the future. Keywords: global system for mobile communications(gsm); traffic; blocking; carrier frequency configuration; the best wireless * 1. Introduction The development of GSM network has turned into a mature and stable stage at present, and the size of GSM network was large. Currently, however, the proportion between investment and mobile income is far from satisfaction. Here emerge some problems that some cells were free all the time, on the contrary, some cells were super busy. And the of cell is unreasonable, which results in the wireless of the whole network is not very high. Currently, the literatures about the best cell wireless research are general based on the cell carrier frequency configuration and control indicators to finally get the best traffic and. However, to a large extent, cell traffic was affected by user s behavior, which resulting in cell *Corresponding author. Tel.: address: shizhf@139.com Published by Elsevier Ltd. doi: /j.proeng Open access under CC BY-NC-ND license.

2 304 Zhi LIU et al. / Procedia Engineering 24 (2011) configuration requirements will change. Based on a city of a month s data of all cells statistical in this paper, analyses the key indicator of the city s GSM network traffic, gives the best carrier configurations in different traffic range of GSM network and the best wireless rate. 2. The relationship between the best cell carrier frequency configuration and the busy traffic blocking rate. The wireless blocking rate includes SDCCH blocking rate and TCH blocking rate. However, there are many factors which affecting the SDCCH blocking rate, such as,sdchh channel configuration number,cell location, Access parameter settings. But, in most cases, the SDCCH blocking can be eliminated by parameter optimization. This article only takes the impact of TCH blocking into consideration and ignore the SDCCH blocking. The ideas of best configuration in cell carrier frequency are run as follows: Cell traffic statistics Range partition in busy traffic cell The number of cell carrier frequency,tch channel and its busy blocking of each range Blocking rate and the percentage of blocking cell relations Reference the definition of blocking cell Relationship between the blocking rate cell and the number of carrier frequency Best carrier frequency configuration and of different traffic interval in each cell According to the maximum of daily traffic, obtains the cell busy traffic. By the statistics of the maximum of cell s blocking rate in a busy traffic, we get the busy blocking rate of the cell. Take handover factors into account, the blocking rate is defined as: TCH blocking rate (including handover) =The number of TCH occupancy failures (including handover)/the number of TCH request (including handover) 100% Through statistics a large number of historical busy traffic data in current network, analyses the cell busy congestion proportion and cell carrier frequency configuration number relationship in each busy traffic interval. In the actual project, the busy cell is defined as busy congestion rate more than 3%. According to the cell blocking control indicator, the proportion of busy cell in city will not exceed 2%.Through draw the proportion which the busy cell takes in different busy traffic intervals, get the cell s best carrier frequency configuration in different busy traffic intervals.

3 Zhi LIU et al. / Procedia Engineering 24 (2011) As for some busy traffic intervals, fig.1 and fig.2 have showed us that with the increasing number of cell carrier frequency, the ratio of busy cell is declining constantly. Right now, we just take two curves (the 12-13erl curve and the20-21erl curve) into account, the ratio of busy cell is increasing when we add the number of cell carrier frequency. The analysis of the current network data have showed us, in this case, cells with low carrier frequency are in a limited proportion, so, there is an increasing tendency,but overall,the curve was declined gradually. And it can be seen from the figures that the cell carrier frequency is obviously too large when take the busy traffic in contrast, which will give rise to a surplus in the cell channel and low wireless rate. According to the definition of busy cell, find the cell best carrier frequency configuration number in different busy traffic intervals. We calculated the busy traffic interval and the best cell carrier frequency configuration, comparing results show in Table 1. Table 1. The best cell carrier frequency configuration

4 306 Zhi LIU et al. / Procedia Engineering 24 (2011) interval(erl) 3. Best cell wireless best cell carrier frequency configuration interval(erl) best cell carrier frequency configuration 0~1 1trx 20~21 5trx 1~2 1trx 21~22 5trx 2~3 2trx 22~23 5trx 3~4 2trx 23~24 6trx 4~5 2trx 24~25 6trx 5~6 3trx 25~26 6trx 6~7 3trx 26~27 6trx 7~8 3trx 27~28 6trx 8~9 3trx 28~29 6trx 9~10 3trx 29~30 7trx 10~11 4trx 30~31 7trx 11~12 4trx 31~32 7trx 12~13 4trx 32~33 7trx 13~14 4trx 33~34 7trx 14~15 4trx 34~35 7trx 15~16 4trx 35~36 8trx 16~17 5trx 36~37 8trx 17~18 5trx 37~38 8trx 18~19 5trx 38~39 8trx 19~20 5trx 39~40 8trx In order to reasonably evaluate the cell wireless rate of current network, introduces the conception of cell best wireless rate base on the cell best carrier frequency configuration number. The conception of best cell wireless rate is: under certain blocking rates, the maximum wireless rate base on the best carrier frequencies configuration number. The formula is: Best cell wireless =cell s busy traffic/cell s best traffic (1) In formula (1), cell s best traffic is the best carrier channel configuration number corresponding to the ErlB traffic.there is uncertainty in cell traffic, so, the best cell wireless rate is just an ideal number, is a continuous approximation process in practical engineering. 4. The Reasonable Evaluation of Cell Wireless Utilization Rate Using best cell wireless, can evaluate the current network's each cell wireless rate rationally. In order to give an reasonable assessment on the level of cell wireless rate. Reaserch should focus on the proximity of current network s cell wireless rate and the best cell wireless rate. Just like table2 shows to us: Table 2.The comparison between current network s cell wireless rate and the best wireless rate inter-val(erl) the current network cell the best rate inter-val(erl) the current network cell the best rate 0~1Erl 8.69% 21.41% 13~14Erl 68.59% 73.98% 1~2Erl 16.37% 50.57% 14~15Erl 74.35% 80.00%

5 Zhi LIU et al. / Procedia Engineering 24 (2011) ~3Erl 25.45% 34.76% 15~16Erl 74.86% 83.97% 3~4Erl 27.32% 42.87% 16~17Erl 60.02% 67.48% 4~5Erl 31.10% 59.72% 17~18Erl 65.39% 74.73% 5~6Erl 36.30% 41.18% 18~19Erl 71.59% 79.21% 6~7Erl 43.59% 51.27% 19~20Erl 83.17% 84.82% 7~8Erl 51.43% 63.23% 20~21Erl 81.79% 84.13% 8~9Erl 54.36% 70.47% 21~22Erl 81.28% 85.64% 9~10Erl 59.74% 76.18% 22~23Erl 82.71% 94.83% 10~11Erl 59.33% 56.83% 23~24Erl 68.19% 75.37% 11~12Erl 62.77% 61.16% 24~25Erl 69.62% 79.92% 12~13Erl 66.66% 67.37% It can be seen from table2 that there are lots of cells wireless rate is still low. According to the information of cell s carrier frequency configuration, we get that some cell s carrier frequency configuration in current network is still unreasonable, it didn t find the standard configuration according to the cell s actual traffic. In the actual project, according to the absorption capacity of cell traffic, keep change the cell configuration to save the channel resources of carrier frequency which is in an increasing tense. If we control the blocking rate effectively we can get a higher wireless rate. 5. Conclusion From the perspective of cell s blocking rate, this article gives us a method to evaluate the cell s carrier frequency configuration, which enriched the previous studies in idea and calculation aspects. This paper analyses the carrier frequency configuration by cell s historic traffic data, and we get the best cell wireless rate. In this way, the actual situation of cell s carrier frequency requirements can be reflected more clearly. It also can prove that the actual carrier frequency configuration of current network is reasonable. The paper can give some significant guides to the channel configuration, such as when shall we increase the channel or reduce. Acknowledgements The authors would like to acknowledge the financial support from the Xinjiang Mobile Communication Company. References [1] Han binjie. GSM principle and network optimization [M].beijing: Mechanic industry Press,2001 [2] Wang Dingding,Ling Wenjia. Apply optimum wireless rate evaluate GSM wireless network [J] Mobile communications.2008,32(8): [3] Xu Changsheng,Ai Xiuqing. Research in Utilization Ratio of Wireless Channel [J].Telecom engineering technology and standardization, [4] Ge Haiping, Wu Song, Gou Guangxue. A Calculation on GSM Wireless Network Channel Utilization Ratio[J]. Designing Techniques of Posts and Telecommunications.2007(4):32-36 [5] Wu Junling, Yang Zhaohui, Guo Yongming, Gao Shengmei. Research on the Inflection Point of Wireless Resource Efficiency and the Enlarging Threshold for GSM Network[J]. Telecom Engineering Technics and Standardization.2010,8:50-53 [6] He Caixia. How to improve the rate of wireless[j].communications world 2007,31 [7] Sun Rushi.GSM digital mobile communication engineering. [M] Posts & Telecom Press.2002 [8] Li Weizhang.Mobile data communications technology and business [M]. Posts & Telecom Press,