A-QL: Part 2 -BER Measurement

A-QL (Asynchronous Quick-Link) is a Screen-2-Camera operating mode being standardized at the IEEE 802.15.7m.

This post introduces the BER measurement method and the performance of A-QL system.

See this video demo for the BER measurement scenario:

 


Experimental Setup

The scenario for measuring BER is illustrated in Figure 1.

1.png
Figure 1 – BER measurement scenarioEnter a caption

The bit rate is measured at three layers as illustrated in Figure 2.

2.png
Figure 2 – BER measurement at three layers

The evaluation of BER under the impacts of distance and perspective distortion is made to verify the reliable performance of the A-QL system. The entire Tx size is set at 8cm×8cm for all the BER measurement. The PN sequence is typically used for the BER measurement; however, for a better monitoring purpose, the practical measurement of BER herein is based on a known data text message to transmit by A-QL code. The error measured results at three layers, layer one without error correction, layer two with a convolutional code, and layer three with RS and CC code.

 


BER Measurement Results

The measurement results are shown in Table 1, Table 2, and Table 3.

Table 1 – The count of bit and error at A-QL receiver under the zero-angle viewing

Distance (m)

1.5

3

4.5

Bits received 1128240 1130400 139680
Count of error (layer 1) 151 17848 19757
Count of error (layer 2) 0 0 6627
Count of error (layer 3) 0 0 2935

Table 2 – The count of bit and error at A-QL receiver under the 30-degree viewing

Distance (m)

1.5

3

4.5

Bits received 1018080 1044000 493200
Count of error (layer 1) 67121 261495 91509
Count of error (layer 2) 3448 54659 22845
Count of error (layer 3) 0 0 7379

Table 3 – The count of bit and error at A-QL receiver under the 60-degree viewing

Distance (m)

1.5

3

4.5

Bits received 442080 615600 514600
Count of error (layer 1) 70162 111953 213950
Count of error (layer 2) 19526 33881 133486
Count of error (layer 3) 1935 5475 72145

 

-----------BER graph --0 degree.JPG
Figure 3- BER of A-QL system under the zero-perspective viewing angle condition

 

-----------BER graph --30 degree.JPG
Figure 4 – BER of A-QL system under the 30-degree perspective viewing angle condition
-----------BER graph --60 degree.JPG
Figure 5 – BER of A-QL system under the 60-degree perspective viewing angle condition

 


Conclusion

The measurements of BER under the impacts of communication distance and the perspective viewing angle are illustrated in Figure 3, Figure 4, and Figure 5. It is notable that the recorded performance of A-QL system is significantly reliable. The short conclusion from the BER measurement is:

  • For BER 10-5 requirement, A-QL operates reliably as far as a 3m distance within perspective angle 30-degree.
  • For lower BER requirement (such as in between 10-2 and 10-3), A-QL can support as far as 4m with a wider perspective angle (60-degree view).

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