Patent Application
20070064681
The embodiments herein relates generally to methods and systems that transmit and receive communication data and more particularly, that operate using discontinuous transmission activity to conserve battery power.
The use of portable electronic devices has increased in recent years. Cellular telephones, in particular, have become commonplace with the public. Many of these devices require a battery for portability purposes which provides a limited supply of power. The devices commonly employ a vocoder to reduce the system bandwidth and conserve power during voice communication. The vocoder is a device which converts analog speech waveforms into digital signals. The digital signals are then typically transmitted to other portable electronic devices where they are decoded and played out of a speaker to a user at the receiving portable device.
The vocoder generally includes a voice activity detector to determine when speech is present and when speech is not present. When speech is present, the vocoder employs sophisticated signal processing routines to compress the data prior to transmission. When the voice activity detector determines a lack of speech present, the vocoder inserts comfort noise frames to serve as background noise frames. The vocoder generates comfort noise frames which signify that the vocoder is operating in discontinuous transmission mode (DTX). During DTX, the vocoder transmits fewer frames with the comfort noise frames spaced over longer time intervals.
The communication device transmits data frames including comfort noise frames processed by the vocoder to other communication devices. The data generally passes through multiple communication base stations or base receivers before reaching the intended recipient. A base station generally opens a communication channel with a sending unit, establishes a communication link with a receiving unit, processes the data, and sends the data to the receiving unit across the established communication link. The base station may decode the data, apply its own form of audio equalization, and re-encode the data to account for equalization effects across the communication channel. The communication device that receives the data is unaware that the base station or receiver has processed the audio signal. The communication device that sent the data is also not aware of any post processing applied to the data during the communication process. The resulting speech decoded by the vocoder of the receiving communication device may be of a different sound nature than that of the original speech that was encoded by the vocoder of the sending communication device due to the intermediate processing at the base station or receiver. In this instance, the communication devices are unable to accurately represent the original speech nature because they do not have knowledge of the processing effects incurred during communication. In other words, the processing performed on a communication channel is based on an assumed environment and not reflective of an actual environment.
The method and system concerns a method for monitoring a data channel for discontinuous transmission activity. The method includes the steps of identifying a source of modification of the discontinuous transmission activity based on receipt of an identifier packet, and applying an equalization based on the source identified in view of the identifier packet. The method can also include the step of modifying the identifier packet during discontinuous transmission activity over a communication channel. The method can also include the step of preserving the identifier packet over the communication channel. As an example, a source can modify the identifier packet over a communication network, where the source of modification of the discontinuous transmission activity can be a mobile communication device or a transcoder.
The method can further include the steps of generating an audio signal from data received on the data channel, and applying the equalization to the audio signal in view of the identifier packet. The method can additionally include marking an identifier packet within a first communication device during discontinuous transmission activity, and transmitting the identifier packet over a communication channel to a second communication device. As an example, the identifier packet can be modified over a communication channel during discontinuous transmission activity, where the modification associates the identifier packet with the source. Accordingly, the equalization can further include compensating for an audio equalization applied at the source.
The method can also include the steps of counting a number of consecutive audio frames received, and generating a comfort noise update when a pre-specified number of consecutive audio frames are counted. As an example, the pre-specified number can be at least a minimum number of audio frames representative of a voice utterance.
The present method and system also concerns a system for monitoring a data channel for discontinuous transmission activity. The system can include a monitoring unit, in which the monitoring unit can identify a source of the discontinuous transmission activity based on receipt of an identifier packet, and an equalizer coupled to the monitoring unit. When the monitoring unit determines that the identifier packet has been modified by the source over a communication channel, the equalizer can apply a compensatory equalization associated with the identified source to compensate for equalization applied at the source. The system can also include suitable software and/or circuitry to carry out the processes described above.
The system can also include a processor communicatively coupled to the monitoring unit to modify the identifier packet over a communication channel during discontinuous transmission activity. As an example the identifier packet can be modified to be one of an audio frame type, a silence frame type, a null frame type, or an invalid frame type. The identifier packet can be modified prior to being received by the monitoring unit, where the modification associates the identifier packet with the source. The processor can reside within a mobile communication device or a base receiver for modifying the identifier packet.
The system can further include a marker unit communicatively coupled to the monitoring unit to create an identifier packet in a first communication device, where the identifier packet can be modified within a communication network during discontinuous transmission activity, and the identifier packet can be received by a second communication device, where the second communication device can include the monitoring unit and the equalizer.
The system can also include an audio module connected to the equalizer that can receive data from the data channel and can generate an audio signal from the data received, and where the equalizer can apply compensatory equalization to the audio signal in view of the identifier packet to compensate for equalization applied to the audio signal at the source. The system can additionally include a logic unit coupled to the monitoring unit that can count a number of consecutive audio frames received from the data channel, and a controller connected to the logic unit that can update comfort noise generated by an audio module when a pre-specified number of consecutive audio frames are counted by the logic unit, when the comfort noise is differentially encoded from the last audio frame received.
As an example, the controller can disable comfort noise generation when the pre-specified number of consecutive audio frames represents a voice utterance length shorter than the minimal voice length a human can vocalize. As another example, the controller can enable comfort noise generation when the pre-specified number of consecutive audio frames is of a length at least representative of a voice utterance length a human can vocalize.
In another embodiment, a system for monitoring a data channel for discontinuous transmission activity based on receipt of an identifier packet can include a marker unit that can mark an identifier packet within a data stream during discontinuous transmission activity, where the identifier packet can be transmitted from a first communication device to a second communication device over a communication channel, and a monitoring unit communicatively coupled to the marker unit that can identify a source that modified the identifier packet over the communication channel during discontinuous transmission activity. The system can further include an audio module cooperatively connected to the monitoring unit that can generate an audio signal from the data stream received over the communication channel, and an equalizer coupled to the monitoring unit, where the equalizer can apply a compensatory equalization to the audio signal to account for equalization applied at the source.
The features of the system, which are believed to be novel, are set forth with particularity in the appended claims. The embodiments herein, can be understood by reference to the following description, taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:
While the specification concludes with claims defining the features of the embodiments of the invention that are regarded as novel, it is believed that the method and system will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
As required, detailed embodiments of the present method and system are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the embodiments of the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the embodiment herein.
The terms “a” or “an,” as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. The terms “program,” “software application,” and the like as used herein, are defined as a sequence of instructions designed for execution on a computer system. A program, computer program, or software application may include a subroutine, a function, a procedure, an object method, an object implementation, an executable application, an applet, a servlet, a source code, an object code, a shared library/dynamic load library and/or other sequence of instructions designed for execution on a computer system.
The embodiment presents a system and method for monitoring a data channel for discontinuous transmission activity. For example, a transmitting unit can initiate discontinuous transmission activity and transmit communication data during the discontinuous transmission activity to a receiving unit. The receiving unit can identify a source of modification of the discontinuous transmission activity based on receipt of an identifier packet and apply an equalization based on the source identified in view of the identifier packet. This equalization can be tailored to compensate for an audio equalization applied at the source when the source is accordingly identified.
Referring to
In one arrangement, the transmitting unit 102 can communicate voice data over the communication network 104 to the receiving unit 106. For example, during a voice call, the transmitting unit 102 can transmit voice data representing both voice and silence information such as comfort noise to the receiving unit 106.
It should also be noted that the transmitting unit 102 is not limited to transmitting signals and that the receiving unit 106 is not limited to receiving signals. These terms are merely meant to distinguish the transmitting unit 102 from the receiving unit 106. As such, the transmitting unit 102 can receive any suitable type of communication signals. Similarly, the receiving unit 106 can transmit any suitable type of communication signals. As an example the transmitting unit 102 and receiving unit 106 can mobile communication units, such as cellular telephones, personal digital assistants, two-way radios, etc. Of course, the transmitting unit 102 can be any electronic device that is capable of at least encoding data, and the receiving unit can be any electronic device that is capable of at least decoding data.
The transmitting unit 102 and the receiving unit 106 can also be referred to as portable computing devices, both of which can be loaded with a computer program having a plurality of code sections. These code sections can be executable by the portable computing devices (102, 106) for causing the portable computing devices (102, 106) to perform the inventive methods that will be described below.
Referring to
In one arrangement, the base receiver 201 can process data when the data packet is in a format not common to both the transmitting unit 102 and the receiving unit 106. For example, the base receiver 201 can interpret descriptive information within the data packet such as the type of vocoder used to compress the data. Based on the descriptive information, the base receiver 201 can process and render the data through a transcoding operation into a format that is acceptable to both the transmitting unit 102 and the receiving unit 106. The base receiver 207 can forward the data packets without processing in a pass-through mode if the transmitting unit 102 and the receiving unit 106 each utilize the same type of vocoder. Also, the data packets can be processed in tandem by both the first transcoder 203 and the second transcoder 204 if separate vocoders in the transmitter 102 and receiver 106 are employed.
Referring again to
In one arrangement, the receiving unit 106 can include a monitoring unit 210, an audio module 212, an equalizer 214, and an optional processor 215. The monitoring unit 210 can be coupled to the audio module 212, which can be coupled to the equalizer 214. Briefly, the monitoring unit 210, can monitor a data channel for discontinuous transmission activity (DTX). Discontinuous transmission activity can occur when the transmitting unit 102 determines that a user is not speaking into the mobile communication device. The transmitting unit 102 can identify periods of silence between speech and elect to send comfort noise data in place of voice data. The comfort noise data can be transmitted less frequently than voice data to conserve battery power. During DTX, the transmitting unit 102 can send data packets with header information that identifies the data packet as one of audio or comfort noise, for instance. The audio module 212, can generate an audio signal from the received data and can produce speech for audio data and silence for comfort noise data. The equalizer can be communicatively coupled to the monitoring unit 210 and apply an equalization to the audio signal as directed by the monitoring unit 210.
Referring to
Referring to
At step 401, the method 400 can start. At step 402, an identifier packet within a first communication device can be marked during discontinuous transmission activity. One way to mark an identifier packet is to change the descriptive header of a data packet to another header type.
For example, referring to
At step 404, the identifier packet can be modified over a communication channel during discontinuous transmission activity. For example, referring to
It is also possible that the base receivers 201 or 207 will not pass the data packets to the first transcoder 203 when it recognizes the vocoder data format as one common to the transmitting unit 102 and the receiving unit 106. In this condition, the base receiver 201 or 207, can forward the packets through without further processing by the transcoders 203 or 204, except for the replacement of empty frame slots with null frames, which is considered a pass-through mode.
At step 406, a source of modification of the discontinuous transmission activity based on receipt of an identifier packet can be identified over the communication channel. Referring to
At step 408, an audio signal from data received on the communication channel can be generated. For example, referring to
At step 410, an equalization based on the source identified can be applied in view of the identifier packet. Referring to
Referring to
At step 804, packets of data representing DTX data for a typical section of silence during speech can be transmitted. During transmission, the marking unit 202 of
At 808 the first transcoder 203 (XCDR1) can convert audio frames (A) to speech and CNU frames (C) and null frames (n) to comfort noise to produce an audio signal. The produced comfort noise within the audio signal can represent the silence regions of speech. When 3 or more consecutive invalid frames are received, the first transcoder 203 can decode them into silence frames. When less than 3 invalid frames are received, the transcoder 203 can issue a frame repeat which during DTX can produce comfort noise frames. Since invalid frames are inter-dispersed with CNU frames, the transcoder 203 (XCDR1) can generate silence for the invalid frames.
At step 810, intermediate processing such as audio equalization can occur during the tandem operation between the first transcoder 203 (XCDR1) and the second transcoder 204 (XCDR2) after the data is converted to an audio signal. For example, the base receiver 201 can apply various types of equalization during a tandem operation where the equalization can be applied to account for high frequency capacitance losses during transmission. At step 810, the first transcoder 203 can convert invalid frame types to silence which can be re-encoded to comfort noise frame types by the second transcoder 204. The tandem decoding and encoding by transcoders 203 and 204 can remove the invalid frame thereby modifying the identifier packet. The identifier packet will not be received by the receiver unit 106.
At step 812, the second transcoder 204 encodes the speech and silence into a vocoder data format acceptable to the receiver unit 106. The second transcoder 204 can transmit every frame without empty slots because it is not power limited. Frame transmissions from the second transcoder 204 to the receiving unit 106 can be continuous since the second transcoder 204 does not employ DTX. The second transcoder 204 converts silence to CNU frames and does not insert invalid frames. At step 814, the receiving unit 106 can receive audio (A) and comfort noise frames (CNU) without inter-dispersed invalid (I) frames. The receiving unit 106 decodes received audio and comfort noise data packets and converts them to speech and silence, respectively.
It is also possible that the base receiver operates in pass-through mode. For example, referring to
Referring to
With reference to
For example, referring to
Referring to
For example, referring to
For example, referring to
It is necessary to disable comfort noise update when a spurious audio frame is received because comfort noise generation is based on the last good audio frame received. For example, at location 718, the audio frame serves as the referential basis for the 3 proceeding comfort noise frames (silence frames) which are differentially encoded from the audio frame at 716. If the audio frame was erroneous, each of the comfort noise frames received would produce silence not representative of the background noise conditions at the transmitter 102. The logic unit 216 and controller 218 serve to prevent isolated audio frames from being used as the referential basis frame. At location 720, the logic unit 216 has counted a proper number of consecutive audio frames and accordingly decrements the count down to zero. This implies that true voice activity has been identified and any proceeding comfort noise frames can be properly decoded.
Where applicable, the present embodiments of the invention can be realized in hardware, software or a combination of hardware and software. Any kind of computer system or other apparatus adapted for carrying out the methods described herein are suitable. A typical combination of hardware and software can be a mobile communications device with a computer program that, when being loaded and executed, can control the mobile communications device such that it carries out the methods described herein. Portions of the present method and system may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein and which when loaded in a computer system, is able to carry out these methods.
While the preferred embodiments of the invention have been illustrated and described, it will be clear that the embodiments of the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present embodiments of the invention as defined by the appended claims.
