Patent Publication Number: US-2007115937-A1

Title: Network device and method for testing voice quality and communication system using the same

Description:
FIELD OF THE INVENTION  
      The invention relates to a network device, and more particularly to a network device with voice quality test function.  
     DESCRIPTION OF RELATED ART  
      VoIP (Voice over Internet Protocol) protocol utilizes an open network to transmit video and audio data. Since real-time voice transmission over a network is implemented by connecting a traditional Public Switched Telephone Network (PSTN) telephone to the Internet via a network device such as a voice gateway, a user only needs to pay an Internet fee and a local call fee while making a long-distance call. Therefore, communication fees for long-distance calling using the VoIP are much lower than those incurred when using a conventional long-distance carrier via the PSTN telephone.  
      However, due to the instability of the Internet, voice quality with VoIP is less stable than with conventional means, therefore a network phone provider is required to test voice quality with each VoIP call in real time to ensure quality. A traditional solution is connecting a voice gateway with a Voice Quality Tester (VQT). Thus, each voice gateway needs a corresponding VQT, thereby increasing the overall network cost.  
     SUMMARY OF THE INVENTION  
      A network device for testing voice quality is provided. The network device includes a parsing module, a test module and a processing module. The parsing module is for receiving a data packet transmitted over the Internet and parsing data in the data packet. The test module is for comparing parsed data with corresponding parameters in a parameter list, and sending a test signal according to a comparison result. The processing module is for outputting a processing signal to a remote manager based on the test signal.  
      A communication system is also provided. The communication system includes Internet, a network device, and a terminal device. The network device is for testing voice quality, and includes a parsing module, a test module, and a processing module. The parsing module is for receiving a data packet transmitted over the Internet and parsing data in the data packet. The test module is for comparing parsed data with corresponding parameters in a parameter list, and sending a test signal according to a comparison result. The processing module is for outputting a processing signal to a remote manager based on the test signal. The terminal device is connected to the Internet via the network device.  
      A method for testing voice quality is further provided. The method includes receiving a data packet from the Internet, parsing data of the data packet, reading corresponding parameters in a parameter list, comparing parsed data of the data packet with the corresponding parameters in the parameter list to test whether the parsed data are normal, and sending a processing signal if the parsed data of the data packet is abnormal.  
      Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  illustrates an application environment of a network device in accordance with a exemplary embodiment of the invention;  
       FIG. 2  is a block diagram of the network device of  FIG. 1 ;  
       FIG. 3  is a parameter list in accordance with the exemplary embodiment of the invention;  
       FIG. 4  is a flow chart of a voice quality test method in accordance with another embodiment of the invention; and  
       FIG. 5  is a detailed flow chart of the voice quality test method of  FIG. 4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  illustrates an application environment of a network device  20  in accordance with a exemplary embodiment of the invention. A plurality of terminal devices  30  are connected to the Internet  10  via several network devices  20 , and communicate with each other over the Internet  10 . The network device  20  also communicates with a remote manager  40 . In this embodiment, the terminal device  30  is a Public Switched Telephone Network (PSTN) telephone, the network device  20  is a voice gateway with voice test function, and the remote manager  40  is a server.  
      The network device  20  transforms a telephone signal from the terminal device  30  into a data packet, and transmits the data packet to another network device  20  over the Internet  10 . After receiving the data packet, the network device  20  transforms the data packet into the telephone signal and transmits the telephone signal to another terminal device  30  connected therewith, thereby a communication between different terminal devices  30  is established. In the process of communicating between different terminal devices  30 , the network device  20  tests voice quality in real time, and then sends a processing signal to the remote manager  40 . In this embodiment, the data packet is a real-time protocol/real-time control protocol (RTP/RTCP) data packet.  
       FIG. 2  is a block diagram of the network device  20  of  FIG. 1 . The network device  20  includes a parsing module  210 , a test module  220 , a storage module  230 , and a processing module  240 . The parsing module  210  is for receiving a data packet transmitted over the Internet  10  and parsing data in the data packet. In this embodiment, parsed data include codec type, along with period, loss rate, jitter, and time delay of the data packet. The test module  220  is for comparing the parsed data with corresponding parameters in a parameter list (shown in  FIG. 3 ), and sending a test signal based on a comparison result. The storage module  230  is connected with the test module  220 , and is for storing the parameter list. In this embodiment, the storage module  230  is a flash memory. The processing module  240  is for outputting the processing signal to the remote manager  40  according to the test signal.  
       FIG. 3  is a parameter list in accordance with the exemplary embodiment of the invention. The perceptual analysis measurement system (PAMS) is employed as a standard of testing the voice quality. The PAMS has different values representing accuracy of different voice quality tests. The larger a PAMS value is, the higher the accuracy of the voice quality test will be. In this embodiment, the parameter list is built based on the PAMS value of 3.3. The parameter list includes three types of codec standards: G.711, G.729 and G.723. Each of the three standards corresponds to the loss rate, the jitter and the time delay for periods of 10 ms, 20 ms, and 30 ms. For example, when the codec type is G.711 and the period is 10 ms, the loss rate, the jitter and the time delay are 16%, 50 ms, and 125 ms respectively.  
      Upon receiving the parsed data of the data packet from the parsing module  210 , the test module  220  compares the parsed data of the data packet with corresponding parameters in the parameter list. In this embodiment, the codec type and the period of the data packet are G711 and 10 ms, respectively. The test module  220  first determines whether the loss rate of the data packet is greater than that (16%) in the parameter list. If the loss rate of the data packet is greater than that in the parameter list, this indicates the loss rate of the data packet is abnormal, and the test module  220  sends the test signal to the processing module  240 . The processing module  240  then outputs the processing signal to the remote manager  40  based on the test signal. If the loss rate of the data packet is smaller than that in the parameter list, this indicates the loss rate of the data packet is normal, and the test module  220  then determines whether the jitter of the data packet is greater than that (50 ms) in the parameter list.  
      If the jitter of the data packet is greater than that in the parameter list, this indicates the jitter of the data packet is abnormal, and the test module  220  sends the test signal to the processing module  240 . The processing module  240  then outputs the processing signal to the remote manager  40  based on the test signal. If the jitter of the data packet is less than that in the parameter list, this indicates the jitter of the data packet is normal, and the test module  220  then determines whether the time delay of the data packet is longer than that (125 ms) in the parameter list.  
      If the time delay of the data packet is longer than that in the parameter list, this indicates the time delay of the data packet is abnormal, and the test module  220  sends the test signal to the processing module  240 . The processing module  240  then outputs the processing signal to the remote manager  40  based on the test signal. If the time delay of the data packet is shorter than that in the parameter list, this indicates the time delay of the data packet is normal, the test module  220  then resends the request to the parsing module  210 , and the next data packet is tested. In other words, if the parsed data of all data packets are normal, voice quality can be guaranteed.  
      In this embodiment, the processing signal sent by the processing module  240  may be a Syslog packet or a Trap packet, which can be set based on a user&#39;s request. When the parsed data of the data packet is regarded as abnormal, the processing module  240  sends the Syslog packet or the Trap packet to the remote manager  40 , in order to notify the remote manager  40  to perform processing and maintenance, thereby ensuring the voice quality of each telephone in the network.  
       FIG. 4  is a flow chart of a voice quality test method in accordance with another exemplary embodiment of the invention. In step S 410 , the parsing module  210  receives the data packet from the Internet  10  and parses the data of the data packet. In step S 420 , the test module  220  receives the parsed data from the parsing module  210 . In step S 430 , the test module  220  reads the corresponding parameters in the parameter list from the storage module  230 . In step S 440 , the test module  220  compares the parsed data of the data packet with the corresponding parameters in the parameter list to determine whether the parsed data are normal. If the parsed data are normal, the process returns to step S 420 . If the parsed data are abnormal, the process proceeds to step S 450 , where the test module  220  sends the test signal to the processing module  240  according to a comparison result. In step S 460 , the processing module  240  outputs the processing signal to the remote manager  40  based on the test signal.  
       FIG. 5  illustrates a detailed flow chart of the voice quality test method of  FIG. 4 . The flowchart of  FIG. 5  is similar to that of  FIG. 4 , but shows more detailed steps for implementing step S 440  of  FIG. 4 . In step S 441 , the test module  220  compares the period of the data packet with that in the parameter list, in order to determine whether the period of the data packet is normal. If the period of the data packet is abnormal, the process proceeds to step S 450  described above. If the period of the data packet is normal, the process proceeds to step S 443 , where the test module  220  compares the jitter of the data packet with that in the parameter list, in order to determine whether the jitter of the data packet is normal. If the jitter of the data packet is abnormal, the process proceeds to step S 450  described above. If the jitter of the data packet is normal, the process proceeds to step S 445 , where the test module  220  compares the time delay of the data packet with that in the parameter list, in order to determine whether the time delay of the data packet is normal. If the time delay of the data packet is abnormal, the process proceeds to step S 450  described above. If the time delay of the data packet is normal, the process returns to step S 420 , where the test module  220  receives data of the next data packet from the parsing module  210 . If the time delay of the data packet is abnormal, the process proceeds to step S 450  described above.  
      It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments.