Abstract - WiMAX as an alternative technology of the wireless broadband internet service provider technique and Radio over Fiber (RoF) as a technique that employs fiber optic communication technologies to transmit radio- frequency (RF) modulated standard signals for today's wireless and mobile applications. Green radio communication means that the power consumption of the communication systems could be minimized by removing some of the electrical active components and equipment by replacing the passive photonic devices and centralizing the signal processing. We have proposed and demonstrated the improvement of WiMAX power efficiency in green communication by utilizing a radio over fiber system. The simulation has been presented for a WiMAX signal transmitted through single mode fiber optic for 80Km and 5Km on the air. The demonstration results show high Signal-to-Noise-Ratio (SNR), extensive power reduction of up to 90% in WiMAX-RoF and a high power loss of WiMAX signal deployed through air.
Keywords - Radio-over-Fiber, World interoperability for Microwave Access (WiMAX).
WiMAX as an alternative technology of the wireless broadband internet service provider is the replacement of the wired broadband (DSL) as a standards-based technology enabling the delivery of last mile wireless broadband access. WiMAX facilitates fixed, nomadic, portable and, shortly, mobile wireless broadband connectivity without the need for line-of-sight communication of end-users with base station transceivers. In a typical cell size deployment of between three to ten kilometers, for fixed and portable wireless access network applications WiMAX systems can be expected to deliver capacity of up to 40 Mbps per channel. Due to the increase of bandwidth, WiMAX enables simultaneous support of hundreds of businesses with T-1 speed connectivity and thousands of residences with DSL speed connectivity. Mobile network applications are expected to provide capacity of up to 15 Mbps within a typical cell radius deployment of up to 3 kilometers. As expected, WiMAX technology will be incorporated in notebook computers and PDAs presently, giving urban areas and cities the possibility to become “metro zones” for portable outdoor broadband wireless access.
Radio over Fiber (RoF) systems have been considered as a type of the communication network infrastructure, which use fiber optic communication techniques to transmit radio-frequency (RF) modulated signals for wireless applications. The potential advantages range from allowing transmission of WiMAX signals in their untreated form to antennas where no RF signal processing beyond amplification is required, simplification of the transmission equipment and reduced power and noise transmission.
Green radio communication means that the power consumption of the communication systems could be minimized by removing some of the electrical active components and equipment by replacing the passive photonic devices and centralizing the signal processing. RoF system is the future network technology which is able to satisfy the demands for decreasing electromagnetic smoking, wireless traffic, power, noise, cost, and antenna size and increasing frequency, bandwidth, data rate and capacity and eventually improves the spectral efficacy. Broadband radio services like WiMAX are growing and therefore causing a renewed focus on the optimum network infrastructures having the ability to transmit signals between base stations and antennas. The signal processing on RF carrier, such as frequency up- conversion, and multiplexing, has been performed at the BS before feeding to the antenna. RoF enables the centralization of the RF signal processing functions in one shared location (Central Station), and the further use of optical fiber to distribute the RF signals to the Radio Access Units (RAU).
This paper has been focused to promote the valueable performance of the RoF technologies to provide efficient solutions for the massive deployment of WiMAX technologies, gaining the advantages of reduced power attenuation in the wireless system with utilizing the optical fiber technology, in addition to the increased transmission distance for WiMAX signal transmission. The green communication systems have been presented by transmitting the WiMAX signal to long distance. Using the RoF technology due to the distinguishable low power attenuation of the optical fiber compared to the traditional electrical wired and wireless communication transmission systems.
II. WiMAX Theoretical Analysis
Fig. 1 shows the downlink model that transmites WiMAX signal to the end-user by using the RoF technology to the WiMAX radio access unit (RAU) transceiver. The RoF consists of the Laser diode, single mode fiber and photo detector diode PIN. The laser model has been designed in Matlab considered for laser Eq.” (1)” and “(2)” and the laser specification in Appendix [A].
Equation (1) describes the optical power and Eq.” (2)” gives the photon density1,2.
Abbildung in dieser Leseprobe nicht enthalten
1 H. Al-Rewashed and S. Komaki, Radio over Fiber Technologies for Mobile Communications Networks, Ed., Norwood: Artech House, pp.85-86, 2002.
2 M. Dehghan, P.Derakhshan-Barjoei, “A novel dynamic analysis and simulation for quantum- well distributed feedback laser (QW-DFB)” Progress In Electromagnetic Research B, Vol. 3, 105-114, 2008