Alamouti Transmit Diversity for Energy Efficient Femtocells

With the ever increasing demand for wireless broadband, design of energy efficient systems is paramount. Femtocells, small self installable wireless base stations, are currently being deployed as a solution to the coverage problems faced by mobile operators, particularly in indoor environments. This paper outlines the framework for evaluating the performance of multiple antenna transmit diversity techniques, based on the Alamouti scheme, relevant to minimizing femtocell transmission power. Simulation results for experiments run on appropriate femtocell channel models are provided. The presented material is given in the context of current third generation systems based on the W-CDMA air interface, however the techniques presented can be extended to future OFDM based systems. Appropriate green solutions need to consider issues of implementation complexity and embodiment which are also discussed.