Telefonaktiebolaget Lm Ericsson (publ)

Stefan Wilhelm Jung

Peter Galyas

Lars Westberg

Johan Tobias Andersson

Johan Karoly Peter Galyas

Per Hallkvist

A telecommunications system and method are disclosed for mapping a Transcoder/Rate Adaptor (TRAU) protocol onto a User Datagram Protocol (UDP) for use in an Internet Protocol (IP) based Base Station System (BSS) architecture. All in-band control bits in the TRAU protocol are not relevant when using the UDP protocol. Therefore, when speech information is mapped onto a UDP datagram for transfer to a Channel Codec Unit(CCU) in a Base Transceiver Station (BTS), some of the information normally transferred between a CCU and the TRAU can be removed. For example, a Time Alignment command included in some of frame types is not needed, and should be removed. In addition, bits relating to a frame structure, such as TRAU synchronization bits, tail bits and spare control bits, should be removed from all frame types. Furthermore, a new control bit that contains a sequence number must be added to handle reordering of a packet data stream.

Mapping of transcoder/rate adaptor unit protocols onto user datagram protocols

A circuit emulation method with garbage removal is used to convert a circuit-switched network for packet-switched transmissions while reusing as much of the existing circuit-switched infrastructure as possible. The garbage removal function removes unnecessary information from a packet before it can be transported, which increases the transport efficiency and decreases the transport delay.

Emulating circuit-switched communications in a packet-switched environment

A method for maintaining synchronization between a base transceiver station (BTS) and an interworking function (IWF) within a cellular communications network is disclosed. The method utilizes a synchronization procedure between the IWF and the BTS that makes the IWF aware of propagation delays between the IWF and BTS. The IWF utilizes this information to adapt to the delays such that the correct sequence is unpacked uplink when obtained from the base transceiver station. The IWF also uses synchronization data to control transmissions from the IWF to the BTS such that frame numbers and timeslots are received at the BTS in the correct sequence.

Method for propagation delay control

A system and method are provided for improving speech quality for signals divided into a frame structure. Speech information in a signal is detected, and a lost or corrupted transmitted frame is detected. The lost or corrupted frame is replaced by a suitable frame if a number of frames represented e.g., by a counter value, exceeds a predetermined value. The counter value may be changed, depending on whether the system is in a comfort noise generation state or in a muting period. The frame may be replaced by a frame representing mainly background noise, generated at the transmitting end during speech pauses or at the receiving end, or such a frame and a correctly received frame. The predetermined value may be the length of a muting period or may be the number of lost or corrupted frames preceding a speech frame. A first of the correctly received speech frames that follows a number of lost or corrupted frames may also be replaced. The output frames gradually approach pure speech frames.

System, arrangement, and method for replacing corrupted speech frames

A method for protecting the transmission of network independent clocking and status information over an air interface between a mobile station and base transceiver station is disclosed. The method involves defining a parallel logical channel between the mobile station and base transceiver station to carry network independent clocking and status information. The network independent clocking and status information are removed from the data stream of the traffic channel and transmitted on the parallel channel over the air interface. Alternatively, a buffer may be used in conjunction with or singly to process the data stream of the traffic channel to delete or insert bits or characters to minimize or eliminate the need for network independent clocking information.

Method for reducing interference within signaling data over an air

A synchronization frame is first formatted and transmitted in accordance with the Global System for Mobile (GSM) 08.60 specification. After an initial synchronization procedure is accomplished between a transcoder/rate adaptor unit (TRAU) and a particular base transceiver station (BTS) serving a mobile station, a modified GSM 08.60 frame is thereafter used to transport greater user data payload across the established communications link. The modified frame replaces the synchronization bits included in the GSM 08.60 formatted data frame with user data to increase data payload from the conventional 13.5 Kbit/s to a more desirable 14.4 Kbit/s without altering the standardized 16 Kbit/s transmission rate supported by the IWF and the BTS.

Growing community of inventors

Brottby, Sweden

Stefan Wilhelm Jung