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wdm optical interfaces for future fiber radio systems phần 3

Tham khảo tài liệu 'wdm optical interfaces for future fiber radio systems phần 3', kỹ thuật - công nghệ, kĩ thuật viễn thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 2 Literature Review enabling the fibre feeder network to support the required large number of BSs to service a certain geographical area. The introduction of OSSB C modulation as well as tandem single sideband modulation enables increased spectral efficiency by reducing the required spectral-band for an optical mm-wave channel in addition to mitigating the effect of fibre chromatic dispersion due to ODSB C modulation format 59-61 112-122 . The tandem single sideband modulation effectively doubles the capacity of the mm-wave fibre-radio systems while compared to the conventional ODSB C based systems 121-122 . However the use of WDM in fibre feeder networks can resolve the challenge by enabling transport of multiple optically modulated mm-wave signals feeding multiple antenna BSs through one fibre 15-16 23 36-39 . The following section reviews the literatures towards the implementation of WDM fibre feeder network in mm-wave fibre-radio systems. 2.3.1 Wavelength Division Multiplexed MM-Wave Fibre-Radio WDM is an elegant and effective way to increase the capacity of the fibre optic feeder networks in mm-wave fibre radio systems. In the WDM incorporated feeder networks optical mm-wave channels each carried by a separate wavelength are transmitted to from the BSs via the CO through a single fibre that provides quantum increase in network capacity without the need for laying new fibre 15-16 23 36-39 44 89 92-93 123-129 . It also simplifies the network upgrades and the deployment of additional BSs while support multiple interactive services for future broadband wireless access communications 15 36-37 125-126 . Fig. 2.12 shows the general concept of a typical mm-wave fibre-radio system incorporating WDM. In the downlink direction optical mm-wave channels spaced at an effective WDM separation are generated in the CO by using WDM optical sources and are passed through a suitable multiplexer that aggregates them to a composite signal. The multiplexed signals are then .