Huawei Technologies Co Ltd, the world's largest telecommunications equipment maker, said it would invest more than $4 billion in fixed broadband technology research and development in the next three years.

Huawei, which has shifted its focus to the mobile device market in recent years, said in a statement on Thursday that fixed broadband - the pipes connecting homes and offices - remained a "key direction for strategic investment".

The Shenzhen-based company said it would research basic technologies such as photonics used in fiber optic cables as well as software-defined networking.