Abstract:
The invention provides a wireless communication apparatus with performance simulation function. The wireless communication apparatus includes a channel emulator and at least one noise generator; therefore a real transmission environment can be simulated inside the wireless communication apparatus to thereby accelerate the testing process. Moreover, as this invention sets a random noise generator in front of the FFT, an approximate AWGN effect will be generated when the wireless communication apparatus is under test.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a wireless communication apparatus, and more particularly, to a wireless communication apparatus with a channel emulator or a noise generator. 
         [0003]    2. Description of the Prior Art 
         [0004]    In a conventional testing process, a fixed pattern is first fed into a communication chip, and then compared with a demodulation result of the communication chip to verify whether the modulating/demodulating function of the communication chip is normal. Usually, a transmitter and receiver inside the communication chip are connected to each other by a loopback to accelerate the testing process. In this way, the testing process does not require external circuits. The interior of the communication chip is equal to an ideal communication environment if there is no interference source disposed in the loopback. The conditions for testing the communication chip are therefore not real conditions for signal transmission, causing the communication chip fail to reach the desired functions when the communication chip is utilized in a real environment. 
       SUMMARY OF THE INVENTION 
       [0005]    One objective of the present invention is therefore to provide a wireless communication apparatus with performance simulation function. By building a channel emulator and a noise generator inside the wireless communication apparatus, an external signal transmission environment is simulated in the interior of the communication chip to accelerate the testing process for mass production and evaluate the performance of the wireless communication apparatus when the wireless communication apparatus is developed. 
         [0006]    According to an exemplary embodiment of the present invention, a network communication apparatus is disclosed. The network communication apparatus comprises a transmitted data processing unit, for processing transmitted data to output a processed signal; a channel simulating unit, coupled to the transmitted data processing unit, for simulating status of a channel and performing channel simulation on the processed signal outputted by the transmitted data processing unit to generate a simulated signal; and a selecting unit receiving the processed signal and the simulated signal, for selectively outputting one of the processed signal and the simulated signal according to a selecting signal, wherein when the network communication apparatus is under test, the selecting unit outputs the simulated signal according to the selecting signal, and when the network communication apparatus is utilized to transmit signals, the selecting unit outputs the processed signal according to the selecting signal. 
         [0007]    According to another exemplary embodiment of the present invention, a network communication apparatus is disclosed. The network communication apparatus comprises a transmitted data processing unit, for processing transmitted data to output a processed signal; a channel simulating unit, coupled to the transmitted data processing unit, for simulating status of a channel and performing channel simulation on the processed signal outputted by the transmitted data processing unit to generate a simulated signal; and a received data processing unit, for processing the simulated signal outputted by the channel simulating unit to output an outputted data. 
         [0008]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a diagram of a wireless communication apparatus under a test mode according to an exemplary embodiment of the present invention. 
           [0010]      FIG. 2  is a diagram of a channel emulator shown in  FIG. 1  according to the exemplary embodiment of the present invention. 
           [0011]      FIG. 3  is a diagram of a binary noise generator implemented in the wireless communication apparatus of  FIG. 1  according to the exemplary embodiment of the present invention. 
           [0012]      FIG. 4  is a diagram of a wireless communication apparatus according to another exemplary embodiment of the present invention. 
           [0013]      FIG. 5  is a diagram of a channel emulator according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Please refer to  FIG. 1 , which is a diagram of a wireless communication apparatus  100  under a test mode according to an exemplary embodiment of the present invention. As shown in  FIG. 1 , the wireless communication apparatus  100  takes an example of a single input single output (SISO) orthogonal frequency division multiplexing (OFDM) system and comprises a transmitted data processing unit  118 , a channel emulator  116 , a random noise generator  117 , a digital-to-analog converter (DAC)  115 , an analog-to-digital converter (ADC)  125  and a received data processing unit  128 . The transmitted data processing unit  118  comprises an encoder  111  for encoding a transmitted data to generate an encoded signal, an interleaver  112  for interleaving the encoded signal to generate an interleaved signal, a QAM mapping unit  113  for modulating the interleaved signal to generate a modulated signal, and an inverse Fast Fourier Transform (IFFT) unit  114  for performing an IFFT on the modulated signal to generate a time-domain transformed signal and inputting the transformed signal to the channel emulator  116 . 
         [0015]    Next, the channel emulator  116  simulates a channel response of an external communication environment for attenuating the transformed signal to output a simulated signal. The random noise generator  117  also generates simulated noise and adds the simulated noise to the simulated signal. Hence, the signal finally outputted by the DAC  115  is a signal suffering from both channel attenuation and noise interference. After the ADC  125  receives the signal outputted by the DAC  115  and converts the signal from an analog format to a digital format, the signal is fed into and processed by the received data processing unit  128  in order to form an outputted data. Please note that operation of each unit in the received data processing unit  128  is the inverse of a corresponding unit in the transmitted data processing unit  118  and is well known to those skilled in the art, therefore descriptions of the operation of each unit in the received data processing unit  128  is omitted here for brevity. Finally, by analyzing the outputted signal of the received data processing unit  128 , performance of the wireless communication apparatus  100  (for example, a graph representing the relationship between packet error rate (PER) and signal-to-noise ratio (SNR)) under channel attenuation and noise interference is obtained. 
         [0016]    According to an embodiment of the present invention, the output signal of the DAC  115  is inputted to the ADC  125 . However, the signal outputted by the channel emulator  116  and added to the simulated noise generated by the random noise generator  117  can be directly inputted to the received data processing unit  128  in another embodiment. Moreover, the channel emulator  116  and the random noise generator  117  need not be disposed in the wireless communication apparatus  100  at the same positions shown in  FIG. 1 . For example, the channel emulator  116  and the random noise generator  117  may change positions with each other, or the random noise generator  117  can be positioned at the output end of the ADC  125 . These related position replacements all fall within the scope of the present invention. Furthermore, the channel emulator  116  and the random noise generator  117  can operate separately or simultaneously. For example, by enabling the random noise generator  117  and bypassing the channel emulator  116 , performance of the wireless communication apparatus  100  under noise interference can be tested; by enabling the channel emulator  116  and bypassing the random noise generator  117 , performance of the wireless communication apparatus  100  under channel attenuation can be tested; and by enabling both the channel emulator  116  and the random noise generator  117 , performance of the wireless communication apparatus  100  under channel attenuation and noise interference can be tested. In other words, under a condition of not affecting the spirit of the present invention, any reasonable combinations of the channel emulator  116  and the random noise generator  117  shown in  FIG. 1  can accomplish the objective of testing the performance of the wireless communication apparatus  100 . 
         [0017]      FIG. 2  is a diagram of the channel emulator  116  shown in  FIG. 1  according to an exemplary embodiment of the present invention. The channel emulator  116  comprises a finite impulse response filter  202  and a multiplexer  204 . The finite impulse response filter  202  is coupled to an input end S 1  of the channel emulator  116 , wherein the input end S 1  receives the processed signal outputted by the received data processing unit  110 . Parameters C 1  to C L  of the finite impulse response filter  202  can be adjusted by setting a control signal stored in a control register (not shown in  FIG. 2 ) to simulate a variety of channel responses. The number of the parameters (i.e. the value of L) can be decided according to the requirements of testing. The multiplexer  204  comprises two input ends S 2  and S 3 , and one output end S 4 , wherein the first input end S 2  is coupled to the input end S 1  of the channel emulator  116 , the second input end S 3  is coupled to the output end of the finite impulse response filter  202 , and the output end S 4  is coupled to the output end of the channel emulator  116 . In this way, the multiplexer  204  can selectively output the processed signal generated by the transmitted data processing unit  110  or the simulated signal output by the finite impulse response filter  202  to the output end of the channel emulator  116  according to a selecting signal. In this embodiment, the multiplexer  204  outputs the simulated signal according to the selecting signal to perform testing when the wireless communication apparatus  100  is operated in the testing mode, and outputs the processed signal according to the selecting signal to perform signal transmission when the wireless communication apparatus  100  is utilized to transmit signals. It should be noted that the above structure is only an embodiment of the channel emulator  116 , and is not meant to be a limitation of the implementations of the present invention. Therefore, other channel emulator structures able to obtain a substantially similar result (such as a channel emulator structure implementing an infinite impulse response filter) also fall within the scope of the present invention. 
         [0018]    The present invention further provides a mechanism to simulate Additive White Gaussian Noise (AWGN) by utilizing a binary noise generator having a simple structure. Compared to the complex AWGN generator, the mechanism utilizing the binary noise generator can save production cost and complexity of the wireless communication apparatus  100 . Please refer to  FIG. 3 , which is a diagram of a binary noise generator  300  implemented in the wireless communication apparatus  100  according to an exemplary embodiment of the present invention. The amplitude of the binary noise generated by the binary noise generator  300  is adjustable by setting a control signal stored in a control register (not shown in  FIG. 3 ) to adjust parameter W. Please note that the binary noise generated by the binary noise generator  300  is independent and identically distributed (i.i.d). Therefore, according to the central limit theorem, after the binary noise is transformed by the IFFT unit  114  or the FFT unit  124 , the binary noise is equivalent to AWGN at the output end of the IFFT unit  114  or the FFT unit  124 . Based on this principle, when the random noise generator  117  is implemented by the binary noise generator  300  of  FIG. 3 , AWGN required to simulate noise interference can be generated by the binary noise generator  300  having simple structure and original units (i.e. IFFT unit  114  and FFT unit  124 ) of the wireless communication apparatus  100  through coupling the random noise generator  117  preceding the IFFT unit  114  or the FFT unit  124 . In other words, the combination of the binary noise generator  300  and the IFFT unit  114 /FFT unit  124  is substantially equivalent to an AWGN generator. In this way, the overall simulation results will be much closer to the real transmission performance in the external environment. 
         [0019]    Please refer to  FIG. 4 , which is a diagram of a wireless communication apparatus  400  of a multiple-input multiple-output (MIMO) OFDM system according to an exemplary embodiment of the present invention. Similar to the SISO system shown in  FIG. 1 , a MIMO channel emulator  416  and a plurality of random noise generators  417  are coupled between an IFFT unit  414  and a DAC  415  of a transmitting module  410  of the wireless communication apparatus  400 . Since a person skilled in the art can easily appreciate the structures of the transmitting module and a receiving module of the wireless communication apparatus  400  from  FIG. 1 , other units of the transmitting module  410  and the receiving module  420  are omitted in  FIG. 4  for brevity. In this embodiment, the random noise generator  417  in one path is utilized to simulate noise received by one receiving antenna, and has the same structure and operation as the random noise generator  117  in  FIG. 1 . The MIMO channel emulator  416  is utilized to simulate multi-path response between multiple transmitting antennas and multiple receiving antennas. Taking a MIMO system having four transmitting antennas and four receiving antennas as an example, the MIMO channel emulator  416  of this MIMO system is shown in  FIG. 5 . Each finite impulse response filter  502  is utilized to simulate a channel response between a specific transmitting antenna and a specific receiving antenna. For example, the finite impulse response filter  502   a  is utilized to simulate a channel response between a first transmitting antenna and a first receiving antenna; and the finite impulse response filter  502   b  is utilized to simulate a channel response between the first transmitting antenna and a second receiving antenna. Therefore, the MIMO channel emulator  416  comprises 16 finite impulse response filters  502 , and the output of each adder  506  represents an attenuated signal received by each receiving antenna because a receiving antenna of the MIMO system receives signals transmitted by every transmitting antenna. Similar to the multiplexer  204  in the channel emulator  116  shown in  FIG. 2 , an objective of the multiplexer  504  is to allow the MIMO channel emulator  416  to output the processed signal generated by the FFT unit without enabling the finite impulse response filters  502  when the wireless communication apparatus  400  is not operated in the test mode. The finite impulse response filters  502  can be configured to simulate a variety of multi-path responses by setting a control signal stored in a control register (not shown in  FIG. 5 ), wherein the control signal configures the finite impulse response filters  502  by adjusting the parameters of the finite impulse response filters  502 . The number of parameters depends on the requirements of the system. Moreover, under a condition of substantially obtaining a same result, part of the finite impulse response filters  502  can be removed from the MIMO channel emulator  416  in order to decrease the circuit complexity. It should be noted that the above structure is only an embodiment of the MIMO channel emulator  416 , and is not meant to be a limitation of the implementations of the present invention. Other MIMO channel emulator structures able to obtain a substantially same result (such as a channel emulator structure implementing infinite impulse response filters) also fall within the scope of the present invention. 
         [0020]    Similar to the wireless communication apparatus  100  of  FIG. 1 , the MIMO channel emulator  416  and the random noise generators  417  of the wireless communication apparatus  400  need not be disposed at the same positions shown in  FIG. 4 . For example, the MIMO channel emulator  416  and the random noise generators  417  may change positions with each other, or the MIMO channel emulator  416  and the random noise generator  417  can be disposed at any position between a QAM de-mapping unit (not shown) and the IFFT unit  414 . Furthermore, the MIMO channel emulator  416  and the random noise generators  417  can operate separately or simultaneously. The transmitting module  410  and the receiving module  420  need not include the MIMO channel emulator  416  and the random noise generators  417  at the same time: when one of the transmitting module  410  and the receiving module  420  has the MIMO channel emulator  416 , the wireless communication apparatus  400  can simulate the multi-path attenuation of external transmission environment. When one of the transmitting module  410  and the receiving module  420  has the random noise generators  417 , the wireless communication apparatus  400  can simulate the noise interference of the external transmission environment. 
         [0021]    In the above embodiments, both the wireless communication apparatuses  100  and  400  comprise a transmitting module and a receiving module, and the signal output by the transmitting module is transmitted directly by a loopback to the receiving module in the same chip for decoding and testing. However, the present invention is not limited to generate a modulated signal and demodulate the modulated signal in the same chip. 
         [0022]    In another embodiment of testing a chip&#39;s performance, a transmitting module of a first communication chip (e.g. the wireless communication apparatus  100  or  400 ) is connected to a receiving module of a second communication chip (e.g. the wireless communication apparatus  100  or  400 ) via a cable, and a channel emulator or/and a random noise generator is disposed in the transmitting module and/or the receiving module. 
         [0023]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.