THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. 2015 Feb.; 26(2), 171178. http://dx.doi.org/10.5515/kjkiees.2015.26.2.171 ISSN 1226-3133 (Print)ISSN 2288-226X (Online) LTE Compatibility between LTE Cellular Systems and WLAN 조한신 Han-Shin Jo 요약 3GPP long-term evolution(lte) 2.32.4 GHz (2.42.5 GHz). LTE. //. LTE throughput. 11 MHz( AP ) 10 MHz( AP 3 ), 1 % throughput. Abstract 3GPP long-term evolution(lte) band 2.32.4 GHz is adjacent to 2.42.5 GHz band for WLAN, and therefore compatibility study of the two systems is desirable. We propose a dynamic system simulation methodology to investigate the effect of WLAN interference on LTE systems. As capturing space/time/frequency changes in system parameters, the dynamic system simulation can exactly predict real system performance. Using the proposed methodology, we obtain LTE downlink throughput loss for the frequency separation between the two systems. Throughput loss under 1 % is obtained from guard band over 11 MHz(single channel allocation) or 10 MHz(three channel allocation). Key words: LTE, WLAN, Dynamic System Simulation, Compatibility, Guard Band. 서론 Long-term evolution(lte) 4 3 3 rd generation partnership project(3gpp) 2008, 4. 3GPP LTE 44 [1]. 40(2,300 2,400 MHz),, (TDD) LTE [2].,,, 40 LTE, LTE., 40 (2,4012,495 MHz) 2013., 2014 () (No. 2013R1A1A1005731). (Department of Electronics & Control Engineering, Hanbat National University) Manuscript received October 8, 2014 ; Revised December 5, 2014 ; Accepted December 12, 2014. (ID No. 20141008-080) Corresponding Author: Han-Shin Jo (e-mail: hsjo@hanbat.ac.kr) c Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved. 171
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 2, Feb. 2015.,., LTE,. MCL (MCL [3], E-MCL [4], A-MCL [5] ) [6] [8]. MCL (coexistence),.,,.,.,. LTE.,,. //, LTE.,. 2.32.4 GHz LTE [9], 900 MHz LTE [10],[11], TV white space(tvws) (470790 MHz) LTE [12]. [10][12] (co-channel), UHF TV. 2.4 GHz (adjacent channel) LTE. LTE throughput..,.. 동적시스템시뮬레이션기법 2-1 셀형태및기지국과이동국배치 1. 2, 2,. 2. 2 19,. 3, 그림 1. Fig. 1. Dynamic system simulation flowchart. 172
LTE E c /I o 또는. (4),,,,. (4) (5), 2 [13]. 그림 2. 3- ( 19) Fig. 2. 2-tier 3-sector hexagonal cell layout... 2-2 서비스기지국결정. 57,. or or or or (2) (1) I or, i, E c, i i, I, i 56 oc i.,, g p P, P i j., E c /I o. (3). active set ï ì ææ ö ï ü í ç Ec ö = i th sector max = ç, i 1,2, L, 57 ý ïî èè I o øi ø ïþ i j (3) (5) Z, Z i 0, 8.9 db, Z, Z i., 0.5 a = b = 1/ 2, 1. (4) (6) [2]. Gmax ABS (q )., A m = 20ddB, q 3dB 3 db 70 o [10]. max min. 2-3 채널발생및신호대간섭및잡음비계산. (4). (SINR). OFDM SINR. (6) (7) 173
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 2, Feb. 2015.,. 2-4 스케줄링및 MCS 레벨결정을통한 Throughput 산출 / LTE resource block(rb). RB 84(12 7 OFDM ) resource element. (7) RB SINR. Proportional Fairness(PF). P m (n) RB RB. P m (n). P ( n) m = R ( n) [ T ( n) ] a m m m, n. m n, T m (n) fairness throughput, a fair exponent factor. T m (n). (8) (9) RB SINR.. log (11) G M-QAM Shannon gap 2. 1, 3 (,, )., drop drop, throughput.. 간섭분석시나리오및시스템변수 II. AP 3. 1.5 km, AP 300 m., AP.. 2 tier ìæ 1 ö 1 ï ç1 - Tm ( n) + R è tc ø tc Tm ( n + 1) = í ï æ 1 ö ï ç1 - Tm ( n) î è tc ø m ( n) n번째에스케줄이안된경우 n번째에스케줄이된경우 (10),. modulation and coding scheme (MCS). SINR R j = [ G j, G j+ 1), j = 1, L, N, G 1 M-QAM SINR, G = N + 1. (8) 그림 3., AP Fig. 3. The location of base stations, mobile stations, and W- LAN APs. 174
LTE AP. AP,. (13) 그림 4. AP Fig. 4. Guard band and WLAN AP channel allocation., 19,. access point(ap) LTE. AP, AP. AP. 4, 2 AP., 2.4 GHz 14 1(2,412 MHz), 6(2,437 MHz), 11 (2,462 MHz), 1/3., AP 1. LTE throughput. 2 AP LTE throughput. AP LTE throughput. AP throughput Throughput. (7) SINR. AP,, AP,. ACIR(Adjacent Channel Interference Ratio) ( ). throughput AP throughput. 4, 5. 5 15 MHz 1 MHz, throughput., AP 300 m, 0 m 300 m 30 m., AP Y. 3GPP [14],[15] 1. 43 dbm, 1 db 14 db. AP 15 dbm, 6 db. 6 (802.11g). (12) 그림 5. Fig. 5. Guard region. 175
THE JOURNAL OF KOREAN INSTITUTE OF ELECTROMAGNETIC ENGINEERING AND SCIENCE. vol. 26, no. 2, Feb. 2015.. 실험결과 그림 6. Fig. 6. WLAN spectrum mask. 표 1. Table 1. System parameters. LTE WLAN(802.11g) BS MS AP 14 dbi 0 dbi 6 dbi 43dBm 22 dbm 15 dbm 30 m 1.5 m 6 m 7 db 14 db 10 MHz 20 MHz RB / 50 - Noise loor 104 dbm 101 dbm 1,500 m SUI-A AP 300 m 2,412 MHz 2,437 MHz 2,462 MHz 7 ( 1: 0 m, Y=0 m, 2: 150 m, Y=150 m) throughput. AP 300 m 1 AP 212 m., 2 AP 0 m., 2 AP (Channel 1: AP 1, Channel 1-6-11: 1,6,11 1/3 ). Y. AP., AP AP. Channel 1 Y 8 MHz throughput 5 %., 11 MHz, throughput 1 %. 1 % throughput, 11 MHz., Channel1-6-11, 10 MHz. COST231 Hata [16] COST231 Walfish Ikegami [16] 2 GHz. 2.32.4 GHz, LTE WiMAX Stanford University Interim (SUI)-A [17],. log log (14),,. 그림 7. throughput Fig. 7. Throughput loss vs. guard band. 176
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