In a TDMA mobile-to-mobile connection, the end-to-end audio signal quality as well as system performance can be improved by providing digital signal processors the capability to automatically switch configuration such that each digital signal processor in a mobile-to-mobile communication connection can automatically identify a TDMA mobile-to-mobile connection and bypass the speech encoding and decoding processes within the digital signal processors. The two digital signal processors are virtually connected at the channel codecs.

System for tdma mobile-to-mobile vselp codec bypass

A method of reducing speech delay and improving speech quality in digital transmission systems by implementing a single coder-decoder (codec) for an entire speech path from a calling party to a called party. The method is applicable to calls between mobile subscribers and between a mobile subscriber and an H.323 client terminal in a data network. After obtaining location information for the called party, an indication of a requested codec is sent from the calling party to the called party utilizing Integrated Services Data Network User Part (ISUP) or Primary Rate Interface (PRI) out-of-band signaling during call setup. If the called party supports the requested codec, a confirmation of the requested codec is sent from the called party to the calling party. A speech path is then established between the parties, and a single codec translation is performed for the entire speech path. If the called party does not support the calling party's codec, but the serving MSCs for both parties support the calling party's codec, the calling party's codec is utilized all the way to the called party's serving MSC. One additional codec translation is then performed in the called party's serving MSC to convert to the codec supported by the called party.

End-to-end coder/decoder (codec)

A digital cellular communication system supports call forwarding with better speech quality by avoiding unnecessary speech decoding when a call is forwarded from one network or exchange to another. A new information element that contains the network code of an originating mobile services switching center (MSC) is added in an initial address message, so that the address of the originating MSC can be properly determined by a terminating MSC or, if call forwarding has been initiated, by a forwarded-to MSC. A structured dialog is used for sending a speech coding request to the originating MSC in which a return result signal acknowledging the request is sent to the correct receiver in the terminating MSC or, if call forwarding has been initiated, in the forwarded-to MSC.

Call forwarding in a mobile communication system

The invention relates to a method (300, 400, 500) for transmitting information related to tandem free operation, where a cellular network comprising a tandem free operation capable coding-decoding unit is connected to a packet network, an entity, which can be a second network or a terminal, is connected to the packet network and data is transmitted over the packet network between said coding-decoding unit on a first side of the packet network and said entity on a second side of the packet network. The method according to the invention is characterized in that information about the decoding capabilities and tandem free operation capabilities on the first side of the packet network is transmitted (320, 420, 520) over the packet network to the second side of the packet network. The invention relates also to a decoding information exchange arrangement (611), to a gateway (610), to a decoding information transmission arrangement (601) and to a cellular network element (600).

Method for transmitting coding information over packet data network

The invention relates to a method and apparatus for controlling the transition of a bypass capable codec between operative modes, based on a certain characteristic of the audio data signal processed by the codec. The apparatus relies on a control signal to determine when the codec will switch from one mode to another. This control signal reflects a characteristic of the audio data signal received at the apparatus, such as the type of speech activity or the format of the audio data signal. When in the active (non-bypass) mode, the apparatus relies on an additional control signal to switch to the inactive (bypass) mode. This additional control signal is received from a control unit at a remote codec that indicates that the remote codec is also bypass capable, hence the decoder at the first codec and the encoder at the remote codec can switch to the inactive mode to pass between them the compressed data frames.

Method and apparatus for controlling the transition of an audio signal converter between two operative modes based on a certain characteristic of the audio input signal

Multi-rate speech coding is a considerable subject in digital cellular systems using highly efficient speech coding methods. The paper describes network functions for the application of the multi-rate speech coding network. As an example of multi-rate coding, functions of a half rate speech coding method in personal digital cellular (PDC) systems are mainly discussed. One of the functions is a codec bypassed connection control to reduce the degradation of voice quality in communication from a mobile station to a mobile station. We propose speech coding negotiation schemes between the originating and terminating MS for the codec bypassed connection control. We also propose a non-voice service connection control scheme which is necessary to provide non-voice services with the same quality as a full rate coding. >

A. Murase

Papers

Network functions for the application of multi-rate speech coding in digital cellular systems