Pulse or digital communications – Testing
Reexamination Certificate
2001-01-09
2003-04-01
Le, Amanda T. (Department: 2634)
Pulse or digital communications
Testing
C370S241000, C455S423000, C455S067700
Reexamination Certificate
active
06542538
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates to data communication. More particularly, the present invention relates to novel and improved method and apparatus for testing wireless communication channels.
II. Description of the Related Art
Wireless communication systems such as code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, and others are widely used to provide various types of communication such as voice, data, and so on. For these wireless systems, it is highly desirable to utilize the available resources (i.e., bandwidth and transmit power) as efficiently as possible. This typically entails transmitting as much data to as many users within as short a time period as supported by the conditions of the communication links.
To achieve the above goal, the communication links between a transmitting source (e.g., a base station) and the receiving devices (e.g., “connected” remote terminals) within the system may be characterized. Based on the characterized link conditions for the remote terminals, the system may be better able to select a particular set of remote terminals to serve, allocate a portion of the available resources (e.g., transmit power) to each selected remote terminal, and transmit to each remote terminal at a data rate supported by the allocated transmit power and characterized link conditions.
Conventionally, a communication link is characterized by transmitting (e.g., from a base station) a known data pattern (e.g., generated by a defined pseudo-random number generator), receiving the transmitted data pattern, comparing the received data pattern with a locally generated data pattern to determine transmission errors, and reporting the results back to the transmitting source. This “loop-back” testing is typically performed continuously for a number of frames over the desired test interval. The test results are reflective of the performance of the communication link over that test interval.
Many newer generation wireless communication systems are capable of flexible operation. For example, data may be transmitted in bursts and over one or more traffic channels (or physical channels), the data rate may be allowed to vary from frame to frame, the processing of the data may also vary (e.g., from frame to frame and/or from channel to channel), and so on. The conventional loop-back test technique typically characterizes the communication link (e.g., one traffic channel) based on a defined set of test parameters, and may not provide an accurate assessment of the performance of the communication link when the system operates in this flexible manner.
As can be seen, techniques that can be used to characterize a communication link under various flexible operating conditions supported by a wireless communication system are highly desirable.
SUMMARY OF THE INVENTION
The present invention provides various techniques to test a wireless communication link. In one aspect, the testing of a traffic channel is performed via a test data service option (TDSO), which is a service that may be negotiated and connected using the available service configuration and negotiation procedures defined by a particular (CDMA) system and used for other services (e.g., a voice call, a data call). Values for test parameters may be proposed by an entity (e.g., a remote terminal), accepted or rejected by the other entity (e.g., a base station), and alternative values for rejected values may also be provided by the other entity. The negotiation may be performed for each traffic channel to be tested.
In another aspect, to test a traffic channel, test data is generated based on a defined data pattern or a pseudo-random number generator. Sufficient test data may be generated for a test interval (e.g., 10.24 seconds) based on values from the pseudo-random number generator, and the generated test data may be stored to a (circular) buffer. Test data may thereafter be retrieved, as necessary, from a particular section of the buffer to form one or more data blocks for each “active” frame in the test interval in which test data is to be transmitted. The particular section of the buffer from which to retrieve the test data may be identified by a particular “offset” from a current buffer pointer location, and this offset may be determined based on a number from the pseudo-random number generator. Each data block may be appropriately identified by a header to enable concurrent testing of multiple traffic channels and for testing frames having multiple data blocks per frame. In an embodiment, one pseudo-random number generator and one buffer are provided (at the transmission source and also at the receiving device) for each traffic channel, either on the forward or reverse link, to be tested.
A traffic channel may be tested using discontinuous transmission. In this case, a two-state first-order Markov chain may be used to determine whether or not to transmit test data for each frame in the test interval. By selecting the proper probabilities of transitioning between an ON state (signifying transmission of test data) and an OFF state (signifying no transmission of test data) of the Markov chain, the average frame activity and average burst length (two parameters that define a discontinuous transmission) may be defined. The Markov chain may be driven by a second pseudo-random number generator, which may be different than the one used to generate the test data.
At a receiving device, the transmitted test data is received, processed in a complementary manner, and provided to a controller. The controller further directs local generation of the test data based on a pseudo-random number generator, which is synchronized to the generator at the transmitting source. The locally generated test data is stored in a buffer and thereafter retrieved from the buffer (as necessary) and compared against the received test data. Various performance and statistical data may be collected at the remote terminal based on the results of the comparison between the received and generated test data.
The testing of the reverse link may be achieved in similar manner as that for the forward link. Multiple traffic channels on the forward and reverse links may be tested concurrently. Independent testing of the traffic channels is possible by testing each traffic channel based on a respective set of test parameter values. Thus, the forward link traffic channels and reverse link traffic channels may be tested based on symmetric or asymmetric test parameter values. The traffic channels under test may have different frame lengths.
The invention further provides other methods and system elements that implement various aspects, embodiments, and features of the invention, as described in further detail below.
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Fischel Scott Eduard
Mir Idreas A.
Baker Kent D.
Le Amanda T.
Qualcomm Incorporated
Rouse Thomas R.
Wadsworth Philip R.
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