Underwater wireless optical communication system based on partial response shaping technology and TCM technology

A wireless optical communication and partial response technology, applied in baseband systems, optical transmission systems, baseband system components, etc., can solve problems such as signal-to-noise ratio degradation and amplified noise

Pending Publication Date: 2021-08-31
8 Cites 0 Cited by

AI-Extracted Technical Summary

Problems solved by technology

The low bandwidth limitations brought by high-power lasers and high-sensitivity detectors introduce serious intersymbol interference (ISI), and existing channel equalization techniques such as least squares (LS), least mean squares (LMS) and frequency domain equalization The full-response equalizer used in the algorithm (FDE), etc., will amplify the noise whi...
View more

Method used

[0049] Fig. 5(a) is the simulation result. The signal generated by the signal processing module at the transmitting end passes through the channel and adds noise to the signal processing module at the receiving end, so that the noise is white Gaussian noise. Where w/L means least squares equalization, w/PR means partial response equalization, w/T means TCM technology, w/PRPT means partial response equalization, precoding and TCM technology, w/PRIPT means partial response Equalization, interleaving, precoding and TCM techniques. It can be seen from the simulation results that the use of partial response equalization can effectively improve the system performance compared with the traditional least squares equalization. Due to the existence of low frequency cutoff, adding prec...
View more


The invention relates to the field of underwater wireless optical communication, and discloses an underwater wireless optical communication system based on a partial response shaping technology and a TCM technology, which comprises an optical transmitting module, an optical receiving module, a transmitting end signal processing module and a receiving end signal processing module. The optical transmitting module converts the digital signal into an optical signal and then sends the optical signal to the optical receiving module, and the optical receiving module converts the optical signal into the digital signal. The transmitting end signal processing module carries out TCM coding, random interleaving, precoding, up-sampling and root raised cosine filtering on original data, and the receiving end signal processing module carries out resampling, root raised cosine filtering, synchronization, channel estimation, channel equalization, partial response shaping, de-interleaving and maximum likelihood sequence estimation on digital signals to obtain the original data. Compared with a traditional method, a partial response filter is added after full response channel equalization, noise amplification of a high-frequency part can be effectively restrained, the signal-to-noise ratio is increased, the bit error rate is reduced, and performance improvement is verified through simulation and experiments.

Application Domain

Electromagnetic transmission optical aspectsChannel estimation +2

Technology Topic

Root-raised-cosine filterPrecoding +10


  • Underwater wireless optical communication system based on partial response shaping technology and TCM technology
  • Underwater wireless optical communication system based on partial response shaping technology and TCM technology
  • Underwater wireless optical communication system based on partial response shaping technology and TCM technology


  • Experimental program(1)

Example Embodiment

[0040] BRIEF following detailed description of the invention in combination;
[0041] First, to be noted that, as used in the present invention, each of the electronic components (component) are both mature technology, and has a corresponding commercial product. Skilled in the art upon reading comprehension application documents on the basis of their knowledge and grasp of the various software radio digital signal processing skills can reproduce the invention;
[0042] like figure 1 , The TCM and partial response shaping techniques underwater optical communication system based on radio, including a signal generator, a power amplifier, an adjustable attenuator electrical, T-bias, DC power supply module, a laser, a collimator lens, emission end of the watertight compartment, a mirror, a photomultiplier tube, mixed signal oscilloscopes, watertight compartment receiving side, the signal processing module and the receiver side terminal transmit signal processing module;
[0043]The original data is sent to the transmit terminal signal processing module. The digital signal generated by the transmitting terminal signal processing module is loaded into the signal generator through the USB data cable, and the signal generator generated by the power amplifier is enlarged after the power amplifier. Adjust the signal power, the DC power module provides a DC bias to operate the laser within the linear range, and the T-type offset is used to overlap the DC bias, and the output signal of the T-type offset is used to drive the laser after the cable is transmitted. The collimated lens is a convex lens. Lasers and collimated lenses are mounted in the emission end water tank;
[0044] After the optical signal is incident in the water, after two reflections of the mirror, reach the receiving end (during transmission of the actual sea area, due to the field limit, removal of the mirror), the photomultiplier is converted to the electrical signal into the electrical signal to transmit to the mixed signal. The oscilloscope, the mixed signal oscilloscope converts the electrical signal into the digital signal, and the receiving end signal processing module processes the digital signal to restore the original data. The photomultiplier is mounted in the receiving end water tank;
[0045] The wavelength of the laser is 450 nm; the peak value of the signal generator output signal is 0.5V, the sample rate is 400/450/500 msamples / s (corresponding communication rate is 400/450 / 500MBPS); the response band of the power amplifier is 100KHz-75MHz The gain is 37dB; the attenuation value of the adjustable electricity dose is 6db; the DC supplies provided by the DC power supply is 0.4a; the detection wavelength of the photomultiplier is 230 nm-700 nm, the effective detection area is 9 mm; the mixed signal oscilloscope sampling The rate is 625 msamples / s;
[0046] Transmitter signal processing module and receiving signal processing module such as figure 2 As shown, the interferon is the reverse mapping of the interleaver. The signal is sampled having a multiple of 2, the training sequence is 2000, the number of taps of the root rose cosine filter is 101, the random coefficient is 0.01, the length of the random interleaver is 5000, the length of the synchronous sequence is 1000, the full response equalizer The number of taps is 81, the backtrach length of MLS is 20, and the corresponding cutting factor α is 0.1 / 0.4 / 0.7, respectively, when the communication rate is 400/450/500 mbps;
[0047] image 3 For the TCM encoding module, consist of 2/3 volume code encoding and PAM-8 modulation, the output signal R exists 8 levels, r ∈ {-7, -5, -3, -1, + 1, + 3, + 5, + 7};
[0048] Figure 4 For 4 state mesh, where the virtual coil represents x 1 = 1, the solid coil represents x 1 = 0, the dotted line indicates Z 3 = 1, the solid line represents Z 3 = 0, the number up / down in the path indicates the possible output value of the status transfer path. The receiving end uses the Viterbi decoder according to Figure 4 The mesh shown is decoded;
[0049] Figure 5 (a) For the simulation results, the signal generated by the transmit terminal signal processing module passes the receiving end signal processing module by the channel and adds noise, and the noise is Gaussi white noise. Where W / L indicates that the minimum multiplier equalization is used, W / PR represents partial response equalization, W / T represents TCM technology, W / PRPT represents partial response equalization, precoding, and TCM technology, W / pript represents partial response Balance, interleaving, precoding, and TCM technology. As can be seen from the simulation results, the use of partial response equalization can effectively improve system performance than traditional minimum multiplier balancing, due to low frequency cutoff, increased precoding and TCM technology on a partial response balanced basis without brings obvious Performance improvement, which can effectively solve this problem by interleaving technology. Figure 5 (b) is a noise spectrum after the least square equalization, and there is a peak in the low frequency portion and the high frequency portion, and after partial response is balanced, such as Figure 5 As shown in (c), the noise of the high frequency portion is suppressed, and the signal-to-noise ratio is improved, but the low frequency portion still has peaks, suppresses the performance of TCM technology, and introduces interleaving technology, such as Figure 5 (d), the flat noise spectrum is obtained, and the system performance is further enhanced;
[0050] Image 6 In order to transmit a different rate signal after 150 meters, the different rate signals can be transmitted from the figure, and the method proposed in the present invention can reach the communication rate of 500 Mbps, compared to the traditional least square equalization, TCM technology and Partial response balance can bring 14.2%, 9.2%, and 8.0% of communication rates;
[0051] Finally, it should be noted that the above list is only the specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and there are many modifications. One of ordinary skill in the art can directly derive or associate all deformations from the disclosed herein, and should be considered as the scope of the invention.


no PUM

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products