The present invention relates to the field of communication technologies, and in particular, to a Set Top Box (STB) and a net conference terminal, a method, an apparatus, and a system for processing network Quality of Service (QoS).
For a real-time media service based on a packet network, network QoS is critical to the service quality. When the network QoS is low, the service quality deteriorates drastically and is hardly acceptable for a user. If a prompt or an alert is sent to the user when the network QoS deteriorates, the user can know the imminent deterioration of service quality and judge whether the deterioration is caused by the network.
In the prior art, the network QoS is judged in many ways. For example, the network QoS may be determined through detection of packet loss, and the network QoS is regarded as being low when packet loss occurs, and is regarded as being good when no packet loss occurs; or, the network QoS may be judged by sending an Internet Control Message Protocol (ICMP) packet, network delay is detected through the ICMP packet, and a further judgment is made about whether Voice over Internet Protocol (VoIP) can be started for communication, and the user is notified if the VoIP communication is not practicable; or, the network QoS is obtained according to both network delay and the packet loss ratio, and is used to determine the charging data.
In the process of implementing the present invention, the inventor finds at least the following problems in the prior art: Only the packet loss ratio of the network or the network delay is considered in the measurement of the network QoS in the prior art, which leads to low accuracy and high error rates in the result of measuring the network QoS.
Embodiments of the present invention provide an STB, a net conference terminal, a method, an apparatus and a system for processing network QoS, to overcome low accuracy and high error rates in the result of measuring network QoS and implement accurate measurement of the network QoS.
A method for processing network QoS in an embodiment of the present invention includes:
obtaining actual usage information of network quality parameters, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio, and the actual usage information of network quality parameters includes the value of each parameter in the current network; and
obtaining descriptive information of network QoS according to the actual usage information of the network quality parameters.
A network QoS processing apparatus provided in an embodiment of the present invention includes:
a first obtaining module, configured to obtain actual usage information of network quality parameters, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio, and the actual usage information of network quality parameters includes the value of each parameter in the current network; and
a second obtaining module, configured to obtain descriptive information of network QoS according to the actual usage information of the network quality parameters.
A network QoS processing system provided in an embodiment of the present invention includes:
a communication network and a network QoS processing apparatus located in the communication network.
The network QoS processing apparatus is configured to: obtain actual usage information of network quality parameters of the communication network, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio; and obtain descriptive information of network QoS of the communication network according to the actual usage information of the network quality parameters.
An STB provided in an embodiment of the present invention includes: an interface module, a decoding module, an outputting module, and the foregoing network QoS processing apparatus, where the network QoS processing apparatus is connected to the interface module.
A net conference terminal provided in an embodiment of the present invention includes: an interface module, an encoding and decoding module, an outputting module, and the foregoing network QoS processing apparatus, where the network QoS processing apparatus is connected to the interface module.
Through the STB, the net conference terminal, the method, apparatus and system for processing network QoS provided in embodiments of the present invention, the transmission bandwidth is considered in measuring the network QoS, which improves accuracy of the measurement result and implements accurate measurement of the network QoS.
The technical solution of the present invention is described in details below with reference to the accompanying drawings and exemplary embodiments.
In the process of network transmission, the network packet loss ratio, network delay and transmission bandwidth are interrelated. That is, reduction of the transmission bandwidth can be used as a means of decreasing the sending rate of a sender on the network, solving the network congestion, decreasing the network packet loss ratio, and shortening network delay. However, with reduced bandwidth, the service quality is reduced, and the reduced network packet loss ratio and shortened network delay cannot reflect the network QoS accurately, and errors may occur. Therefore, in the embodiments of the present invention, transmission bandwidth is considered in measuring the network QoS.
Step 101: Obtain actual usage information of network quality parameters. That is, the network QoS processing apparatus of the communication network obtains values of the network quality parameters, where the network quality parameters may be a combination of transmission bandwidth and network delay, or a combination of transmission bandwidth and network packet loss ratio, or a combination of transmission bandwidth, network delay and network packet loss ratio.
Step 102: Obtain descriptive information of network QoS according to the actual usage information of the network quality parameters.
In this embodiment, because the transmission bandwidth is considered in the process of measuring the network QoS, the measurement of the network QoS is more accurate, fewer errors occur, and the obtained descriptive information of the network QoS reflects the network QoS more accurately and objectively. The quantitative network QoS data is fed back to the user as a prompt and an alert, which helps the user judge whether the deterioration of the service quality is caused by the network or the terminal. In this embodiment, a function relationship between the network QoS and the network quality parameter is set up through a weight model or Gilbert model, and the obtained values of the network quality parameters are substituted into the function relationship to work out the descriptive information of the network QoS. The method is detailed in the following embodiment.
Step 201: Obtain actual usage information of network quality parameters, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio. The actual usage information of the network quality parameters in this step refers to the value of each parameter in the current network.
Step 202: Obtain weight values of the transmission bandwidth, and network delay and/or network packet loss ratio. The weight values may be determined according to the network type and the quantitative relationship between transmission bandwidth, network delay and network packet loss ratio.
Step 203: Obtain descriptive information of the network QoS according to the weight values, transmission bandwidth, network delay, and/or network packet loss ratio. This step uses a weight model to set up a function relationship between the network QoS and the transmission bandwidth, and network delay and/or network packet loss ratio. The actual usage information (namely, the value of each parameter) of the network quality parameters obtained in step 101 is substituted into the function relationship to obtain the descriptive information of the network QoS. The expression of the weight model is: Q=Ah+Bd+Cp, where Q is descriptive information of the network QoS; A, B, and C represent the weight values of transmission bandwidth b, network delay d and network packet loss ratio p respectively, and A is nonzero.
In this embodiment, a function relationship is set up between the network QoS and the transmission bandwidth, network delay, and/or network packet loss ratio through a weight model, which takes the impact of the transmission bandwidth into consideration and works out more accurate descriptive information of the network QoS.
Step 301: Obtain actual usage information of network quality parameters, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio. Packet size is one of the parameters that affect the network quality, but generally remains unchanged. Therefore, the impact of the packet size may be disregarded.
Step 302: Obtain the initial QoS data of the network quality parameters, namely, obtain the best network transmission bandwidth, best network delay, best network packet loss ratio, worst network transmission bandwidth, worst network delay, and worst network packet loss ratio.
In this step, the network quality parameters are normalized according to the obtained initial QoS data. The preceding best values and worst values may be set by the user, or estimated by the system automatically, for example, estimated according to the network interface type. The best transmission bandwidth may also be determined through capability negotiation. The worst transmission bandwidth is expressed by BB, and the best transmission bandwidth is expressed by GB, and their values may be 64 Kbps and 640 Kbps respectively. The worst network delay is expressed by BD, and the best network delay is expressed by GD, and their values may be 200 ms and 50 ms respectively. The worst network packet loss ratio is expressed by BP, and the best network packet loss ratio is expressed by GP, and their values may be 20% and 0 respectively. The foregoing parameters may be used to make up the initial QoS value (EQ):
Step 303: Normalize the transmission bandwidth, and network delay and/or network packet loss ratio according to the initial QoS data.
In this step, the parameters are normalized to facilitate comparison and calculation. Each parameter is normalized to a value between 0 and 1. In this way, the network QoS data can be restricted to a range between 0 and 1, where 0 represents the worst value and 1 represents the best value. Generally, in the network service range, the network QoS is linearly related to the network quality parameter. Therefore, linear transformation may be applied. The normalization equation is:
In the foregoing formula, x represents a network quality parameter, whose value may be b, d, or p; the corresponding BX and GX represent the worst value and the best value of the network quality parameter respectively; BX is BB, BD, or BP; and GX is GB, GD, or GP. Therefore, the normalized transmission bandwidth b′ is calculated through:
Similarly, the normalized network delay d′ is calculated through:
Similarly, the normalized network packet loss ratio p′ is calculated through:
For example,
the constraint of x ∈ [0,1] is introduced to obtain the normalized expression of the network quality parameter:
Step 304: Obtain the weight values corresponding to the normalized transmission bandwidth, normalized network delay and/or normalized network packet loss ratio respectively.
After the normalized network quality parameters are calculated in step 303, a weight model is used to calculate the weight of the transmission bandwidth b′, weight of the network delay d′, weight of the network packet loss ratio p′. Such weights are expressed as Wb, Wd, and Wp respectively, and Wb is nonzero.
Step 305: Obtain descriptive information of the network QoS according to the weight values, normalized transmission bandwidth, and normalized network delay and/or network packet loss ratio.
In this step, the network QoS (Q) is expressed as:
Because b′, d′ and p′ are normalized parameters, it is appropriate to set Q ∈ [0,1] when Wb+Wd+Wp=1. For example, when Wb, Wd, and Wp are 0.3, 0.3, and 0.4 respectively,
Q=0.3b′+0.3d′+0.4p′, where b′×d′×p≠0.
b×d×p=0 means that when the value of any network QoS parameter reaches its worst value, it is deemed that the network QoS is 0. The weights of the parameters above may be set according to the network conditions or network type. It is also appropriate to consider only the impact of the transmission bandwidth b and the network packet loss ratio p, or the impact of the network bandwidth b and the network delay d.
When only the impact of the transmission bandwidth (b) and the network packet loss ratio (p) on the network QoS is considered, the weight of the network delay (Wd) is set to 0. In this case, the network QoS (Q) is expressed as:
Because b′ and p′ are normalized parameters, it is appropriate to set Q ∈ [0,1] when Wb+Wp=1. For example, when Wb and Wp are 0.4 and 0.6 respectively,
Q=0.4b′+0.6p′, where b′×p′≠0.
b′×d′=0 means that when the value of any network QoS parameter reaches its worst value, it is deemed that the network QoS is 0.
When only the impact of the transmission bandwidth (b) and the network delay (d) on the network QoS is considered, the weight of the network packet loss ratio (Wp) is set to 0. In this case, the network QoS (Q) is expressed as:
Because b′ and d′ are normalized parameters, it is appropriate to set Q ∈ [0,1] when Wb+Wd=1. For example, when Wb and Wd are 0.4 and 0.6 respectively,
Q=0.4b′+0.6d′, where b′×d′≠0.
b′×d′=0 means that when the value of any network QoS parameter reaches its worst value, it is deemed that the network QoS is 0.
After the function relationship between the network QoS and each network quality parameter is obtained, each parameter value in the network is detected and substituted into the foregoing relationship to obtain quantitative network QoS data. The quantitative network QoS data reflects the network quality more objectively and accurately. In the process of measuring the network QoS in the foregoing embodiment, normalization is performed first, which facilitates calculation and comparison between the calculation results.
In the previous embodiment, a function relationship is set up between the descriptive information of the network QoS and the network quality parameter according to the weight model; in this embodiment, a function relationship is set up through a Gilbert model, and the actual usage information of the network quality parameters is obtained first. The network quality parameters include transmission bandwidth, network delay, network packet loss ratio, and packet size.
If the network packet loss ratio is higher than a threshold, the descriptive information of the network QoS is obtained according to the packet size, network delay, and network packet loss ratio, namely, a Gilbert model is used to set up the following relationship:
if the network packet loss ratio is lower than or equal to the packet loss threshold, the descriptive information of the network QoS is obtained according to the transmission bandwidth, and the relationship may be Q=λ×b, which takes the special circumstance of a small packet loss ratio into consideration. In the foregoing relationship, Q is descriptive information of the network QoS, s is packet size, d is network delay, p is network packet loss ratio, b is transmission bandwidth, and a is a packet loss threshold which may be set to 0, or preferably set to 0.0013, or estimated by the system in the specific measurement process and adjusted dynamically; η and λ are set coefficients; η is preferably set to 0.61 and λ is set to 1; α is a set packet loss threshold, which may be set to 0, or preferably set to 0.0015.
In this embodiment, the network quality parameters include transmission bandwidth, network delay, network packet loss ratio, and packet size. The packet size generally keeps unchanged.
It is also appropriate to restrict the descriptive information of the network QoS to a range between 0 and 1, to introduce the best transmission bandwidth, and to set up the following function relationship between the network quality parameter and the descriptive information of the network QoS:
In the formula above, BD is the worst network delay, BP is the worst network packet loss ratio, GB is the best transmission bandwidth, and the best transmission bandwidth (GB) may be determined through capability negotiation.
In this embodiment, a function relationship between the network QoS and each parameter is set up through a Gilbert model; considering that the network QoS still differs even if the network packet loss ratio is 0, the packet size, network delay, network packet loss ratio and transmission bandwidth of the current network are obtained and substituted into the foregoing function relationship to work out the network QoS quantitatively. The value (Q) of the descriptive information of the network QoS ranges between 0 and 1, where 0 represents the worst level and 1 represents the best level. In the foregoing function relationship, the GB in the denominator and the Min function are introduced in order to let the Q value fall within [0, 1], and are optional in practice.
In the embodiments of the preceding method, it is necessary to obtain the transmission bandwidth, network delay, and network packet loss ratio of the network. To measure the network packet loss ratio (p), the receiver needs to collect statistics. For example, if the data is transmitted through the Real-Time Transport Protocol (RTP), the RTP packets are numbered sequentially, and the sequence number is inserted into the RTP packet header. In this way, the receiver can measure the packet loss ratio in a period (T):
p=(Ne−Nr)/Ne
In the formula above, Ne is the number of packets expected to receive, Nr is the number of packets received actually, and the statistic period (T) is generally the time interval of Sender Report (SR) control packets in two consecutive packets, or another preset value.
The network delay (d) is a unidirectional delay, which is the time spent in transmitting a packet from the sender to the receiver, and may be calculated by using many methods. The first method is to measure the Round-Trip Time (RTT), and the network delay is expressed as d=RTT/2. In a practical network environment, the sending delay may differ from the receiving delay sharply. Therefore, it is not accurate to substitute a half of the RTT for the unidirectional delay. An effective method is to measure the unidirectional delay directly. Another method is to synchronize the clock between the sender and the receiver when measuring the unidirectional delay. After the synchronization, the network delay of the receiver can be calculated according to the timestamp directly. The delay d may be expressed as d=Tr−Ts, where Ts is the sending timestamp and Tr is the receiving timestamp.
In an IP network environment, the clock synchronization between the sender and the receiver is generally not precise, and the delay may be calculated in incremental mode, namely, the network delay is calculated according to the difference between unidirectional delays:
d=d
o
+Δd=d
0+[(Tr−Ts)−(Tr0−Ts0)]
In the formula above, d0 is an initial delay value (corresponding to time t0 of the receiver), which may be expressed by a half of the RTT; Δd is a delay change relative to time t0; (Tr−Ts) is a unidirectional delay at the current time and is calculated according to the sending time (Ts) and the receiving time (Tr); (Tr0−Ts0) is a unidirectional delay at time t0 and is calculated according to the sending time (Tr0) and the receiving time (Ts0), and the difference between the two unidirectional delay values is the delay change value, which eliminates the error caused by lack of clock synchronization. Another method for calculating the delay is: adding the delay value at the previous time to the delay difference between the current time and the previous time to obtain the delay.
For the transmission bandwidth b, depending on the network conditions, the current receiving rate of the network interface on the receiver or a previously measured receiving rate of the network interface on the receiver is used as transmission bandwidth. The network conditions include network packet loss ratio and network delay. For example, if the network packet loss ratio is used as the network condition, its initial value may be set to the best bandwidth (GB), and the subsequent values are determined in the following way:
When packet loss occurs, namely, when the network packet loss ratio is higher than the packet loss threshold, the current receiving rate of the network interface on the receiver is used as the transmission bandwidth (b); when no packet loss occurs or the packet loss ratio is very low, namely, when the network packet loss ratio is lower than or equal to a preset threshold, the previously measured bandwidth or the current receiving rate of the network interface on the receiver is used as the current transmission bandwidth (b), whichever is higher. That is:
10072] In the formula above, n is the sequence number of the detected b, namely, the b detected for the nth time; Rr is the receiving rate of the network interface on the receiver; and α is a preset packet loss threshold, and may be set to 0; and Max refers to taking the maximum value.
In the foregoing embodiment, because the network packet loss ratio (p) is calculated in a period, b and d may be average values in the corresponding period in practical calculation.
The current network packet loss ratio (p), current transmission bandwidth (b), current network delay (d) are detected in the foregoing method, and substituted into a relationship set up through a weight model or Gilbert model to calculate the network QoS quantitatively. Because the transmission bandwidth is considered, the calculation result is more accurate and objective.
After the descriptive information of the network QoS is obtained, the descriptive information of the network QoS may be displayed to the user according to a preset display policy. Specifically, the calculated descriptive information of the network QoS (namely, the Q value obtained in the foregoing embodiment) is displayed on the displaying module directly, or the Q value is processed in a certain way, especially, the network QoS data obtained after the normalization is multiplied by 100 so that the value is displayed between 0 and 100. In this way, the user can understand and judge the network QoS. The network QoS may be displayed through graphs intuitively.
On the receiver, the coding algorithm may be adjusted according to the descriptive information of the network QoS. For example, when the Q value is high, namely, when the network QoS is good, the audio coding algorithm such as AAC-LD is applied, which provides good voice quality but requires a high QoS level of the network; when the Q value is low, the G.711 algorithm that requires a moderate QoS level of the network is applied.
After the descriptive information of network QoS is obtained through the foregoing method, the sending bandwidth on the sender can be obtained according to the descriptive information of the network QoS. Specifically, the adjusted sending bandwidth may be set to be in direct proportion to the descriptive information of the network QoS. For example, after the descriptive information (Q) of the network QoS is obtained in any method in the foregoing embodiment, the sending bandwidth is adjusted to K×Q×GB, where K is a scale factor. For example, when Q=0.6, GB is 640 Kbps; when K is 1, the sender is notified to control the sending bit rate within 384 Kbps. When the Q value changes to 0.8, the sender is notified to adjust the transmission bandwidth to 512 Kbps. To avoid frequency adjustment, a Q value change threshold a may be set. For example, the threshold is set to 0.1, and the adjustment is made only if ΔQ is higher than σ. Further, a minimum adjustment interval may be set, namely, the data sender is notified to adjust the transmission bandwidth only when the threshold is fulfilled and the minimum adjustment interval is fulfilled. In this embodiment, the sending bandwidth is adjusted according to the obtained descriptive information of network QoS so that the transmission bandwidth used by the data sender for sending data can change with the change of the network QoS, which improves the network QoS.
In this embodiment, because the transmission bandwidth is considered in the process of measuring the network QoS, the measurement of the network QoS is more accurate, and the obtained descriptive information of the network QoS is more accurate and objective.
In this embodiment, a function relationship is set up between the network QoS and the transmission bandwidth, and network delay and/or network packet loss ratio through a weight model; a weight value is preset according to the network type and the quantitative relationship between the parameters, and then the detected parameter values are substituted into the relationship to obtain the network QoS data. This embodiment takes the impact of the transmission bandwidth into consideration, improves accuracy of the measurement result, and reduces measurement errors.
In this embodiment, the network quality parameters are normalized, and then a weight model is used for calculating, which facilitates the calculation process. Meanwhile, the calculation result falls between 0 and 1, which makes it easier to find change of the network QoS. Moreover, the transmission bandwidth is considered, which improves accuracy of measuring the network QoS and obtains objective descriptive information of the network QoS.
The network QoS processing apparatus provided in the foregoing apparatus embodiment may further include a displaying module.
The apparatus may further include a first sending module 44. The first sending module 44 is configured to generate and send information according to the descriptive information of the network QoS, where the information is used for notifying the sender to adjust the coding algorithm to adapt to different levels of network QoS. Specifically, when the Q value is great, namely, when the network QoS is good, the first sending module 44 uses an audio coding algorithm such as AAC-LD, which provides good voice quality but requires a high QoS level of the network; when the Q value is small, the first sending module 44 uses a G.711 algorithm that requires a moderate QoS level of the network.
The network QoS processing apparatus may further include a second sending module 45, configured to generate and send information according to the descriptive information of the network QoS, where the information is used for notifying the sender to adjust the sending bandwidth. The second sending module may set the adjusted sending bandwidth to be in direct proportion to the descriptive information of the network QoS, for example, adjust the sending bandwidth to K×Q×GB, where K is a scale factor. Afterward, the second sending module sends a notification of the adjustment to the data sender so that the data sender adjusts the sending bandwidth to adapt to the network conditions according to the notification. After obtaining the descriptive information of the network QoS, the second sending module sends the descriptive information to the data sender so that the data sender calculates and adjusts the sending bandwidth. When adjusting the sending bandwidth, in order to prevent too frequent adjustment, conditions of adjustment may be set, and the transmission bandwidth is adjusted only if the conditions are fulfilled. One method is to set a threshold of change of the network QoS.
An STB is provided in an embodiment of the present invention.
A net conference terminal is provided in an embodiment of the present invention.
A network QoS processing system is provided in an embodiment of the present invention. The system includes a communication network and a network QoS processing apparatus located in the communication network. Specifically, the network QoS processing apparatus is configured to: obtain actual usage information of network quality parameters of the communication network, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio; and obtain descriptive information of network QoS of the communication network according to the actual usage information of the network quality parameters.
The network QoS processing apparatus in the foregoing embodiment includes a first obtaining module and a second obtaining module. The first obtaining module is configured to obtain actual usage information of network quality parameters, where the network quality parameters include transmission bandwidth, and network delay and/or network packet loss ratio; and the second obtaining module is configured to obtain descriptive information of network QoS according to the actual usage information of the network quality parameters. The network QoS processing apparatus may further include a displaying module, configured to display the descriptive information of the network QoS according to a preset display policy.
On the basis of the foregoing embodiment, the network QoS processing system may further include a first sending module, configured to generate and send information according to the descriptive information of the network QoS, where the information is used for notifying the sender to adjust the coding algorithm. The network QoS processing system may further include a second sending module, configured to generate and send information according to the descriptive information of the network QoS, where the information is used for notifying the sender to adjust the sending bandwidth.
The network QoS processing system in this embodiment takes the transmission bandwidth into consideration while measuring the network QoS quantitatively. Therefore, the measurement result is more accurate and objective. The network QoS processing apparatus is configured to instruct the data sender to adjust the sending bandwidth to adapt to the actual network conditions according to the obtained descriptive information of the network QoS.
In the foregoing embodiment, the transmission bandwidth, network delay and network packet loss ratio are considered in the process of obtaining the descriptive information of the network QoS, and the packet size may be considered additionally. If the packet size is considered, the network QoS processing apparatus is further configured to obtain actual usage information of network quality parameters of the communication network, where the network quality parameters include transmission bandwidth, network delay, network packet loss ratio, and packet size; and obtain the descriptive information of the network QoS of the communication network according to the actual usage information. Specifically, a function relationship may be set up between the network QoS and the network quality parameter through a Gilbert model, and the obtained actual values of the network quality parameters are substituted into the function relationship to work out the descriptive information of the network QoS. In this embodiment, the packet size is considered along with the factors such as transmission bandwidth in the process of obtaining the descriptive information of the network QoS. Therefore, the selected parameters are more comprehensive, and the obtained descriptive information is more accurate and objective.
In the foregoing embodiment, the communication network may be an IP network which transmits IPTV services. In this case, the network QoS processing apparatus is set on the IP STB, and the IP STB receives the IPTV service while processing the QoS, for example, displaying the descriptive information of the QoS. Further, bidirectional video communication may be performed. In this case, the network QoS processing apparatus is set on the video communication device (such as a videophone or a videoconference terminal). The video communication device is configured to perform the bidirectional video communication service while processing QoS, for example, displaying the descriptive information of the QoS and adjusting the sending bandwidth according to the QoS information. The network QoS processing apparatus in this embodiment may be applied to various media services based on a packet network.
Through the STB, the net conference terminal, the method, apparatus and system for processing network QoS, multiple network quality parameters such as transmission bandwidth are considered in the process of measuring the network QoS, and a function relationship is set up between the network QoS and the network quality parameters through a weight model and a Gilbert model respectively; the obtained values of the network quality parameters (such as network packet loss ratio, network delay, transmission bandwidth, and packet size) are substituted into the function relationship to calculate the network QoS quantitatively and obtain the descriptive information of the network QoS. Because the transmission bandwidth is considered, the measurement result is more accurate and reflects the network QoS more accurately and objectively. Moreover, the descriptive information of the network QoS is displayed to the user in real time so that the user can judge whether the deterioration of the service quality is caused by the network or the terminal. The sending bandwidth of the data sender is adjusted according to the descriptive information of the measured network QoS so that the transmission bandwidth is adaptable to the network conditions.
Finally, it should be noted that the above embodiments are merely provided for describing the technical solution of the present invention, but not intended to limit the present invention. It is apparent that persons skilled in the art can make various modifications, variations, and replacements to the invention without departing from the spirit and scope of the invention. The present invention is intended to cover the modifications, variations, and replacements provided that they fall within the scope of protection defined by the following claims or their equivalents.
Number | Date | Country | Kind |
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200810239101.9 | Dec 2008 | CN | national |
This application is a continuation of International Application No. PCT/CN2009/073616, filed on Aug. 28, 2009, which claims priority to Chinese Patent Application No. 200810239101.9, filed on Dec. 8, 2008, both of which are hereby incorporated by reference in their entireties.
Number | Date | Country | |
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Parent | PCT/CN2009/073616 | Aug 2009 | US |
Child | 13155777 | US |