The aim of the MODAL project is to achieve an innovative, cost competitive solution to the following:
- Definition of optically supported remote microwave and millimetre wave antenna systems for broadband mobile/personal communications and wireless CACs, combining flexibility of deployment and use, with low complexity, high reliability and cost effectiveness for the remote terminal.
- Development of system models to support applications assessment and evaluation of deployment strategies.
- Proof of practicality of system proposals and advanced technologies in the demonstrator.
- A basis for the planning and evolution of future MBS and wireless CAC systems.
The main objective of the MODAL project was to achieve an innovative, cost competitive solution to the following technical challenges:
the definition of optically supported remote microwave and millimetre wave antenna systems for broadband mobile personal communications and wireless customer access connection (CAC) combining flexibility of deployment and use, with low complexity, high reliability and cost effectiveness for the remote terminal;
the development of system models to support applications assessment and the evaluation of deployment strategies;
to prove the practicality of system proposals and advanced technologies in a demonstrator;
to provide a basis for the planning and systems evolution of future mobile broadband system (MBS) and wireless CAC systems based upon MODALtechnology.
A basic system model has been developed which incorporates dimensioning of the demonstrator and detailed design of system components.
A novel optical source has been assembled which can generate 2 stable optical signals whose frequencies differ by the required millimetre wave frequency. Very narrow linewidth (less than 100 Hz) millimetre wave signals have been achieved.
To realise a return link with high dynamic range a laser model has been developed and an integrated tuned optical receiver has been designed. The target system parameters of MODAL have been defined.
A system study results in detailed modelling to define target requirements, to provide an assessment of performance trade-offs and to guide much of the detailed design work.
Using a dual line optical source and coherent mixing, modulated mm-wave generation and transmission will be achieved at 30 and 60 GHz. A high speed optical modulator and a 60 GHz PIN photodiode will be developed and used in a unidirectional optical 60/65 GHz mm-wave link.
For the return path, mm-wave mixing at the antenna site will provide down conversion to 2 GHz of the FDMA mm-wave mobile signals, to be conveyed to the base station over fibre using wavelength division multiplexing (WDM) at 1300 nm. Device linearisation and compensating non-linear signal processing operations will be explored to accommodate the wide dynamic range.
The system will be integrated into a 30 GHz demonstrator (the microwave optical duplex antenna link). Evaluation measurements will be made and results related to model predictions.
- How optical fibre technology may best be used to provide remote delivery of high quality digital multi-channel microwave signals.
- How optical fibre technology can effectively support remote delivery and generation of millimetre wave signals.
- How the technology employed may be effectively and economically combined to support remote millimetre wave antennas for mobile/personal/micro cellular systems for broadband communications.
The proving of technological developments by this project will lay the foundation for future broadband fibre networks conveying multi-channel mm-wave signals to enhance the deployment options for mobile/wireless systems. The project will thereby contribute specifically to common functional specifications in the areas of UMTS, MBS and CAC.
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