by P. Sriploy, M. Uthansakul and R. Wongsan Investigation into GPRS Transmission Employing Switched Beam Antenna at Mobile Station by P. Sriploy, M. Uthansakul and R. Wongsan

Outline Introduction GPRS Transmission Simulation Conclusion Background GPRS System Smart Antenna System Literature Survey motivation GPRS Transmission Simulation Assumption Results Conclusion Page 2

Introduction GPRS (General Package Radio Service) is a packet oriented Mobile Data Service available to users of Global System for Mobile Communications (GSM) Quality of GPRS transmission  Coding Scheme (CS) Smart antenna system is envisaged to improve the quality of GPRS transmission Coding Scheme C/I Datarate (kbps) CS -1 less than 7 9.05 CS -2 7 – 12 13.4 CS -3 12 - 17 15.6 CS -4 more than 17 21.4 Page 3

Introduction Smart antenna system = array antenna + signal processing unit Benefits better range/coverage greater battery life smaller/lighter handset size increased capacity multipath rejection reduced expense Page 4

Introduction 2 types of smart antenna system: - Switched beam antenna - Adaptive antenna - Switched beam antenna performs similarly to adaptive antenna when employing few antenna elements [5] - Switched beam antenna outperforms adaptive antenna when the desired signal is not sufficiently larger than interferences [5] Page 5

Introduction Literatures For this paper: Concept of smart antenna has been proposed at Base Station to enhance GPRS transmission [6] This results in high cost and complexity For this paper: We propose the idea of using switched beam antenna at Mobile Station to enhance the quality of GPRS transmission Effect of array size reduction on the system throughput is also investigated Page 6

GPRS Transmission PL GPRS Parameter Path Loss TDMA/FDD Reverse Channel: 890 – 915 MHz Forward Channel: 935 – 960 MHz Channel Bandwidth: 200 kHz Duplex Separation: 45 MHz or 3 Time Slots Total Number of RF Duplex Channel: 124 users Path Loss (Fading) (No Fading) received power transmitted power antenna gain at BS antenna gain at user PL Page 7

Computer Simulation Assumption - 100 users  uniformly distributed - Antenna gain: switched beam; 6.76 dB omnidirectional; 0 dB at BS; 14 dB - Mutual coupling effect between the array elements is included Page 8

Simulation Results Average C/I (dB) - Omnidirectional = 7.22 - 0.1λ = 7.45 - 0.2λ = 8.25 - 0.3λ = 11.10 - 0.4λ = 12.95 - 0.5λ = 15.23 switched beam - Switched beam antenna provides better performance compared with omni- directional antenna - Best C/I is obtained from the case when the array antenna is spaced by 0.5λ Page 9

Simulation Results Average throughput (dB) - Omnidirectional = 11.22 - 0.1λ = 11.26 - 0.2λ = 12.45 - 0.3λ = 14.44 - 0.4λ = 14.83 - 0.5λ = 16.56 switched beam Switched beam antenna provides better throughput, specially when we utilize the array having inter-element spacing of 0.5λ Page 10

Simulation Results 40% 13% System throughput decreases as the array spacing is reduced Page 11

Conclusion Utilizing switched beam antenna at Mobile Station enhances the performance of GPRS system Array elements spaced by 0.5λ provides the best performance Array spacing reduction affects the system C/I and throughput Ones can find the provided information useful for designing a switched beam antenna for GPRS system Page 12

End Thank you for attention!! Question? Page 13