TRANSMISSION EQUIPMENT FOR A CONNECTION BETWEEN MOBILE COMMUNICATION NETWORK ELEMENTS AND A METHOD FOR TRANSFERRING DIGITALLY ENCODED SPEECH BETWEEN A FIRST NETWORK ELEMENT AND A SECOND NETWORK ELEMENT

摘要

The invention relates to a method and transmission equipment for a connection between telecommunication network elements, such as exchanges or base station controllers. At both ends of the connection there is a transmission equipment (TRACU1,2) connected to a number of PCM trans- mission channels from the exchange. A lower-capacity interconnecting PCM link in which bits in the PCM samples form subchannels for transmitting lower-rate vocoded speech or data is provided between the transmission equipments. If a PCM coded speech signal in which there is a lower-rate subchannel in one or more least significant bits of the PCM samples is received from the exchange, the content of this subchannel is multiplexed into one of the subchannels in the interconnecting PCM link. If a pure PCM coded speech signal is received from the exchange, it is encoded into a lower-rate vocoded speech signal, and the vocoded speech signal is multiplexed into one of the subchannels of the interconnecting PCM link. At the other end of the connection, the .transmission equipment decodes the vocoded speech signal into PCM samples and the un- decoded content of the subchannel is inserted into the least significant bits of the PCM samples.