A base station for a WCDMA telecommunications network, intended for use in indoor environment to enhance coverage and increase capacity. The base station is designed according to a modular concept, and includes a base station unit having an interface for connection to a power supply, a radio network contoller, and to an antenna, said base station unit having a sandwich structure comprising a rigid metal back plate, a rigid metal front plate, and a main circuit board attached intermediate said back plate and front plate, wherein said main circuit board is cooled by means of self-convection of said back plate and said front plate.