tailieunhanh - TEAM FLY WIRELESS NETWORK DEPLOYMENTS phần 2

Triển khai mạng di động là một phần khoa học, một phần kỹ thuật và nghệ thuật chủ yếu. Điều này là do thực tế là tuyên truyền RF là do "mờ" để rất nhiều rào cản RF và các hiện tượng tán xạ. Xây dựng mã số khác nhau từ nơi này đến nơi làm cho nó thực tế không thể dựa vào các công cụ dự đoán phần mềm. | Ceỉỉuỉar Network Deployment 17 Example N 7 Freq. Group-1 Diversity Ant. Fig. 9 Method of reducing intermod problems based on antenna sharing which reduces power flow by 50 in each path. 6. CONCLUDING REMARKS Cellular network deployment is partly science partly engineering and mostly art. This is due to the fact that RF propagation is fuzzy owing to numerous RF barriers and scattering phenomena. Building codes vary from place to place making it practically impossible to rely on voftware prediction tools. Consequently we end pp with drive test collect data and fine-tune the model. Even then a margin of 8 to 10 dB in receive signal level is allowed in the final design. These arc the realities of RF design with respect to cellular deployment. We have addressed many of these issues in tins paper namely RF propagation C I Frequency planning cell site location intermod issues etc. and proposed possible solutions to enhance capacity and perfomance. If my readers find ths infomation useful I sh be amply rewarded. 18 Chapter 1 1. APPENDIX A. Okumura-Hata Model The Okuniura-l lata model is based on experimental data collected from various urban environments having approximately 15 high-rise buildings. The path loss formula of the model is given by Lp dB 4- f - hb - a hm log hb log d Al where Lp path loss in dB f Frequency in MHz d Distance betweenthe base station end the mobile km hb Effective height of the base station in meters a hm log F - hm - log F - hm Mobile antenna height Eq. Al maybe expressed conveniently as Lp dB L0 dB 4- - log hb log d A2 or more eonveniently as Lp dB Lo dB 10 y log d A3 where L0 dB 4- log f log hb -a hm A4 End y - log hb 10 A5 Eq. AU is plotted in as a function of Oase station ontenna height. It shows that ill a typical urban environment the attenuation slope varies between and 4. Cellular Network Deployment 19 Fig. Al Attenuation slope as a .